Sunday

February 19, 2017
Total # Posts: 37,717

**math**

what is 7x8x4 ?

*December 12, 2016*

**Algebra PLEASE HELP ME**

BC = 11 - (-2) = 13 what is the difference between a height of 8 and a height of 20 ?? Did you look at your diagram?

*December 12, 2016*

**Algebra PLEASE HELP ME**

slope of BC = (8-8)/(11=2) = 0 so BC is a horizontal line Thus the line through A must be a vertical line All vertical lines have the form x = something Look at the given point A, what is its x value ? so the equation of your required line is x = 3 Make a sketch. The base BC ...

*December 12, 2016*

**Math lovely Math**

prob(elephant) = 7/20 prob(tiger) = 6/20 continue ... add them up to make sure they add up to 1, they will! If they don't you messed up

*December 12, 2016*

**Math**

arc = rØ, where Ø is in radians 25 = 7Ø Ø = 25/7 radians

*December 12, 2016*

**Math**

cost per hour = 175/5 = 35 (not bad for babysitting, but then again I haven't needed a babysitter in 70 years) cost = 35t , where t is the number of hours slope is 35 y-intercept is 0 It is a proportion, and it is a function

*December 12, 2016*

**h.p.**

The base of your powers is an arithmetic sequence sum(1) = 1 sum(2 ) = 1+ 4^2 = 17 sum(3) = 17 + 7^2 = 66 sum(4) = 66 + 10^2 = 166 sum(5) = 166 + 13^2 = 335 sum(6) = 335 + 16^2 = 591 ... with the third difference column of 18, we know it must be in the form of a cubic we could...

*December 12, 2016*

**math**

32/9 = 3 5/9 you will have to guess at the 5/9, since your numberline probably has divided the unit in tenths, not ninths so between 3 and 4 , just a bit more than half way between 3 and 4

*December 12, 2016*

**Pre-Calculus**

I don't see "the following function"

*December 12, 2016*

**precalculus**

form y = (3/2)x b:a = 3/2, but a = 3 b/3 = 3/2 2b = 9 b = 9/2 hyperbola: x^2 /9 - y^2/(81/4) = 1 or x^2/9 - 4y^2/81 = 1 or 9x^2 - 4y^2 = 81 whichever form your text considers standard form

*December 12, 2016*

**Calculus**

first number --- x 2nd number ----y 3rd number ---- 40-x-y x + 3y + 4(40-x-y) = 80 x + 3y + 160 - 4x - 4y = 80 -3x- y = -80 3x + y = 80 y = 80-3x product = x(y)(80-x-y) = 80xy - x^2 y - x y^2 = 80x(80-3x) -x^2(80-3x) - x(6400 - 480x + 9x^2) = .... = 160x^2 - 6x^3 d(product)/dx...

*December 12, 2016*

**Math Help**

First of all you don't have an equation, so "cross-multiplication" is a meaningless term. You did not match up the corresponding numbers, which was my whole point, and objection to this question your equation should have been: 24/6 = 18/x or 6/24 = x/18 <--- I...

*December 12, 2016*

**Math Help**

Show me the steps that gave you 72, as I said, I got 4.5 x : 18 = 6 : 24 <-- following corresponding pattern x/18 = 6/24 24x = 108 x = 108/24 = 4.5

*December 12, 2016*

**Math Help**

It is not a matter of choosing an answer. You must determine the answer with some solution. Why did you "choose" that answer? I would assume that the sides are listed in the corresponding order. In that case none of the answers given are correct. I got x = 4.5

*December 12, 2016*

**Calculus**

Since (1-2x-3x^2)/(1+x) = (1+x)(1-3x)/(1+x) = 1 - 3x, x ? - 1 what do you think you should use

*December 12, 2016*

**Algebra**

I divided the 2nd equation by 2 to get the x terms to be both 5x Are you not familiar with the method of elimination? Just like we can multiply each term of an equation by some number, we can also divide each term by some number without changing the value of the equation. (...

*December 12, 2016*

**math**

?x - 6 = x^(1/4) let ?x = t then we have t - 6 = ?t square both sides t^2 - 12t + 36 = t t^2 - 13t + 36 = 0 (t-9)(t-3) = 0 t = 9 or t = 3 if t = 9, then x = 81 if t = 3, then x = 9 since we squared our equation, all answers must be verifies if x = 81 LS = ?81 - 6 = 9-6 = 3 RS...

*December 12, 2016*

**Algebra**

1000 e^(kt) = 1274 e^(5k) = 1.274 take ln of both sides 5k = ln 1.274 k = ln 1.274/5 = .048323... = 4.83 % rounded to the nearest hundreth

*December 12, 2016*

**Math**

y = 1500 (1.071)^t , where t is in hours

*December 12, 2016*

**Math**

As Steve already did this for you, I don't know why you are repeating it. ... Anyway, prob(of your event) = (3/10)(5/10) = 15/100 = 3/20 , which is what Steve had told you.

*December 12, 2016*

**Math**

number for Mr Jones ---- x number for Mr Smith ---- x-500 .03x = .05(x-500 .03x = .05x - 25 -.02x = -25 x = 1250 Mr. Jones sold 1250 widgets and Mr. Smith sold 750 check: .03(1250) = 37.5 .05(750) = 37.5

*December 12, 2016*

**precaculus**

no, tanØ = -1 , not Ø = -1 since (2,-2) is in quadrant IV, Ø = 315° or 7?/4 so one answer is (2?2 , 7?/4) another would be (-2?2, 3?/4)

*December 12, 2016*

**Algebra**

by definition, |anything| ? 0 so |1-4k| must surely be ? -11 for anything inside the absolute value sign

*December 12, 2016*

**pre-calculus**

length --- l width ----w 2l+2w=36 l+w = 18 l = 18-w area = lw = w(18-w) = 18w - w^2 d(area)/dw = 18-2w = 0 for a max of area 2w = 18 w = 9 then l = 18-w = 9 so the area of the base of the box must be a square, 9 by 9 as you probably expected.

*December 12, 2016*

**pre-calculus**

let the length be l let the width be w so 2l + 2w = 36 l + w = 18 l = 18-w area = wl = w(18-w) = 18w - w^2

*December 12, 2016*

**precalculus**

x^2 - 16 = 4y^2 or (x+4)(x-4) = 4y^2 let x = t then t^2 - 16 = 4y^2 y^2 = (t^2 - 16)/4 y = ± ?(t^2 - 16)/2 , -4 ? t ? 4

*December 12, 2016*

**Calculus**

http://www.jiskha.com/display.cgi?id=1481558182

*December 12, 2016*

**Algebra**

Surely you can follow the method I just showed you in your previous question almost identical to this one. Did you even look at my answer ?

*December 12, 2016*

**algebra**

double the 2nd: 5x + 6y = 24 now sub the first one into that 5x + (-5x + 24) = 24 5x - 5x + 24 = 24 0 = 0 , which is a true statement, thus you have an infinite number of solutions.

*December 12, 2016*

**Calculus**

Consider it as the points (1,-4), (2,-4), (3,-3) etc let the function be ax^2 + bx + c = y for: (1,-4) ---> a + b + c = -4 * (2,-4) ---> 4a + 2b + c = -4 ** (3,-3) ---> 9a + 3b + c = -3 *** subtract * from ** 3a + b = 0 # subtract ** from *** 5a + b = 1 ## subtract # ...

*December 12, 2016*

**Calculus**

Just do it. I am sure you can subtract.

*December 12, 2016*

**precalculus**

I would leave the y value in exact form y = r sinØ = -14(?3/2) = -7?3 you also missed the negative sign in your y value exact point (-7, -7?3)

*December 12, 2016*

**pre calculus**

correct: http://www.wolframalpha.com/input/?i=parametric+plot+x%3Dt+,+y%3Dt%5E2%2B10 http://www.wolframalpha.com/input/?i=parametric+plot+x%3Dt%5E3,++y%3Dt%5E6%2B10

*December 12, 2016*

**Calculus**

intersection of y = 12 and y = e^x e^x = 12 x = ln 12 area = ?(12 - e^x)dx from 0 to ln12 = [12x - e^x] from 0 to ln12 = 12ln12 - e^(ln12) - (0 - e^0) = 12ln12 - 12 - 0 + 1 = 12ln12 - 11 http://www.wolframalpha.com/input/?i=area+between+y+%3D+e%5Ex,++y+%3D+12+from+0+to+ln12

*December 12, 2016*

**precalculus**

I think they want you to use a separate graph for each of the values of n to show what happens to the graph as n changes. Wolfram might be of help here: Just change the values in front of the 2nd term to see how it affects the graph. I have shown the graph for n = 3 http://www...

*December 12, 2016*

**quick question regarding math**

If your equation has the solution of all real numbers, then your equation is an "identity". here are the different cases for linear equations: case 1: one unique solution 3x -4 = 2x + 1 3x-2x = 1+4 x = 5 case 2: no solution 3x - 4 = 3x - 5 3x-3x = -5+4 0 = -1 , which...

*December 12, 2016*

**Math**

Not familiar with the notation A^BC for an angle The usual notation is angle ABC, where B would be the vertex of the angle and the containing sides would be AB and BC Explain your notation.

*December 12, 2016*

**Math.**

14x?1/2(4x+6)=3(x?4)?18 14x - 2x - 3 = 3x - 12 - 18 I am sure you can take it from here.

*December 12, 2016*

**math**

200000000 or 200,000,000 would be "two hundred million"

*December 12, 2016*

**Math**

The areas of similar objects are proportional to the square of their corresponding sides. so 28 : x = ?8 : ?25 28/x = 2?2/5 2?2x = 140 x = 70/?2 or 35?2

*December 12, 2016*

**Mathematics**

5 women 7 men, choose 4 a) number of ways with no restriction = C(12, 4) = 495 b) must be 3 men and 1 woman = C(7,3) x C(5,1) = 35 x 5 = 175 c) at least 3 women ---> 3 women or 4 women = C(5,3) x C(7,1) + C(5,4) x C(7,0) = 10x7 + 5x1 = 75

*December 12, 2016*

**math**

let the sides be 3x, 4x, and 5x 3x+4x+5x = 24 12x = 24 x = 2 sub back into my definitions of the sides so the sides are 6, 8, and 10

*December 12, 2016*

**math**

Question makes no sense!

*December 11, 2016*

**algebra**

(9/10)x + 1/x = x times 10 9x + 10/x = 10x times x 9x^2 + 10 = 10x^2 x^2 = 10 x = ?10 check: 1/?10 = 1/?10 *?10/?10 = ?10/10 so (9/10)?10 + 1/?10 = (9/10)?10 + ?10/10 = 10?10/10 = ?10

*December 11, 2016*

**Algebra**

don't make it so complicated, all you want is the coefficients of either the x's or the y's to be the same. 3x +6y = $48.00 , divide by 3 --> x + 2y = 16 2x + 8y = $46.00 , divide by 2 --> x + 4y = 23 subtract them: 2y = 7 y = 3.5 then in x+2y = 16 x + 7 = 16...

*December 11, 2016*

**Algebra**

After a proper definition of your variables, your system is correct to solve, how about multiplying the first by 2, and then subtracting them ? I am sure you can take over from here

*December 11, 2016*

**Pre-Calculus**

I don't know what procedure you learned, but this is how I taught this: step 1: show it to be true for n = 1 LS = 3 RS = 1(4-1) = 3 step 2: assume it is true for n = k that is 3+11+19+..+ (8k-5) = k(4k - 1) step 3: show it then must be true for n = k+1 that is, show 3+11+...

*December 11, 2016*

**MAth**

Ms Sue is correct to state that the mathematical probability is 1/2 But according to the "experimental" data of the hospital, it would be 50/90 or 5/9 Silly question!

*December 11, 2016*

**Geometry**

nope, 382 is not a side of a similar triangle see my reply to your question when you posted it earlier.

*December 11, 2016*

**math**

see http://www.jiskha.com/display.cgi?id=1481507804

*December 11, 2016*

**Algebra!**

number of adult tickets --- x number of student tickets -- 2x 7x + 4(2x) = 45 15x = 45 x = 3 so they bought 3 adult tickets and 6 student tickets. check: is the number of adult tickets half of the student tickets ? YES what is the cost: 7(3) + 4(6) = 45 my answer is correct

*December 11, 2016*

**Geometry Honors**

Make a sketch and use a simple ratio: 22/h = 40/(40+382) 40h = 22(40+382) = 9284 h = 232.1 ft

*December 11, 2016*

**Algebra**

for 1st line: two points are (-3/2, 0) and (0,3) slope = (3-0)/(0+3/2) = 3/(3/2) = 2 so equation of 1st line is y = 2x + 3 2nd line: slope = 3(2) = 6 y intercept = 3 + 28 = 31 equation of 2nd line: y = 6x + 31 intersection: 6x + 31 = 2x+3 4x = -28 x = -7 then y = 2(-7) + 3 = -11

*December 11, 2016*

**Calc**

length of pool --- x width of pool -----y cost = 10x + 5y = 1000 2x + y = 200 y = 200-2x area = xy = x(200-2x) = 200x - 2x^2 d(area)/dx = 200 - 4x = 0 for a max of area 4x=200 x=50 then y = 200-100 = 100 state your conclusion

*December 11, 2016*

**math**

Snowball was in the air as long as h > 0 let's see when h = 0 0 = -16t^2 + 48t + 28 divide by -4 4t^2 - 12t - 7 = 0 (2t + 1)(2t - 7) = 0 so t = -1/2 or t = 7/2 but t ? 0 so the ball was in the air for 7/2 or 3.5 seconds

*December 11, 2016*

**algerbra**

Are you saying: 11?(37x) = 44?37 ???? if so, then ?(37x) = 4?37 square both sides: 37x = 16(37) x = 16

*December 11, 2016*

**math**

number of 2-pointers ---- x number of 3-pointers ----- 16-x 2x + 3(16-x) = 38 solve for x

*December 11, 2016*

**algebra word problem**

lower rate ---- r higher rate ---- r+.015 1100r + 1800(r+.015) = 288 1100r + 1800r + 27 = 288 2900r = 261 r = .09 the one rate was 9% , the other 10.5% check: 1100(.09) + 1800(.105) = 288

*December 11, 2016*

**Math**

2.52 cm = .0252 m

*December 11, 2016*

**Maths**

So, one is chose, leaving 14 others to those from. Number of ways = C(14,3) = 364

*December 11, 2016*

**math**

the volume of similar objects is proportional to the cube of their corresponding sides, so V1 : V2 = 1^3 : 3^3 V1 / 162 = 1/27 V1 = 162/27 = 6 the new volume is 6 cm^3

*December 11, 2016*

**Algebra**

let the first be x let the second be y the third is x-45 x+y > x-45 by 80 ---> x+y = x-45 + 80 x + y = x + 35 y = 35 x + y + x-45 = 194 2x + 35 - 45 = 194 2x = 204 x = 102 the first is 102 the 2nd is 35 the 3rd is 57

*December 10, 2016*

**Algebra**

9|r-2|-10<-73 9|r-2| < -63 |r - 2| < -7 BUT, the absolute value of anything has to be ? 0, so it certainly cannot be ? -7 Your inequation has no solution. Just try some numbers in your solution, they don't work. e.g. for r < 9 , let r = 4 LS = 9|4-2) - 10 = 8 ...

*December 10, 2016*

**geometry**

compare the two lengths of the corresponding dimenstions: lengths: 14.7/4.2 = 3.5 widths : 20.3/5.8 = 3.5 heights: 33.6/9.6 = 3.5 well, how about that ??

*December 10, 2016*

**Algebra**

Something not right here. According to your equation, it is not launched from ground level, but from a height of 4 units. Furthermore it is launched with a downwards velocity of 1 unit of distance/ 1 unit of time domain: t ? 0 check for a typo

*December 10, 2016*

**Algebra**

see my comment at your repeat posting of the same question above.

*December 10, 2016*

**Algebra**

First of all , don't switch to decimals ( 7/6 ? 1.16, it is 1.1666.... ) So you have two points (-7/6 , 0) and (0,7) slope = (7-0)/(0+7/6) = 7/(7/6) = 6 equation of first line : y = 6x + 7 slope of 2nd line = 12 <----- it said twice the first y-intercept of 2nd line = 7...

*December 10, 2016*

**Algebra**

First of all , define your variables 3x + 7y = $46.00 8x + 4y = $75.00 <----- notice correction 3x + 7y = $46.00 (times 8): 24x + 56y = 368 8x + 4y = $75.00 (times 3): 24x + 12y = 225 subtract them: 44y = 143 y = 3.25 go back into one of the original equations to find x, ...

*December 10, 2016*

**Algebra**

equation #1: x - y = 47 equation #2: deals with the number of legs 4x + 2y = 938, or 2x + y = 469 add our two equations: 3x = 516 take over....

*December 10, 2016*

**Maths**

now: Mona ---- x Dad ----- 3x in 12 years: Mona = x+12 Dad = 3x+12 3x+12 = 2(x+12) take over

*December 10, 2016*

**Algebra**

Why do you have L's, W's and x's in your equation ? width ---- w length ---- l equation #1: 2w + 2l = 84 w+l = 42 ** equation #2: "The length of a rectangle is 91 less than six times the width of the rectangle" ---> l = 6w - 91 sub that back into ** w...

*December 10, 2016*

**MATH**

so a point on it is (4,0) y-0 = 3(x-4) y = 3x - 12

*December 10, 2016*

**math**

so it must be a vertical line All vertical lines have equation of the form x = c, where c is a constant look at the point (3,-1) , its x value is 3 so : x = 3 is the equation.

*December 10, 2016*

**V.i.p. Maths**

Bob, I always thought that happened in Indiana. https://en.wikipedia.org/wiki/Indiana_Pi_Bill 22/7 is the best approximation to ? using at most 2 digits as the numerator of the fraction. If you allow 3 digits, the best fraction is 355/113 which differs from ? by only ....

*December 10, 2016*

**Maths**

Make a sketch, drawing the right-angled triangle formed by the chord and the two radii. Find the area of that triangle, very easy find the area of the 1/4 of the circle, very easy subtract those two to get the minor segment Find the area of the whole circle and subtract the ...

*December 10, 2016*

**Algebra**

first of all just divide the 2nd equation by 5 to get n + 2d = 86, the other is n + d = 59 <<---- you had 430 here. subtract them: d = 27 then in n+d = 59 , n+27 = 59 n = 32 She has 27 dimes and 32 nickels check: is 27+32 = 59 for the sum of coins? YES for the value of ...

*December 10, 2016*

**math**

The height creates a right-angled triangle with angles of 30° and 60° so if the base of that triangle is x, then using the ratios of the 30-60-90 triangle, x/1 = 12/?3 x = 12/?3 or 12/?3 *?3/?3 = 4?3 So the base of the equilateral triangle is 8?3 giving you an area of...

*December 10, 2016*

**Math**

Not really familiar with the formulas relating demand function, cost functions and profit, but here is an example of your question. http://math.stackexchange.com/questions/758620/maximized-profit-w-a-cost-demand-function

*December 10, 2016*

**Business Math ( Future ordinary Annuities)**

You should get into the habit of making a time graph on a straight line for these kind of questions. Think of the whole thing as being in two accounts. 1000(1.025^48)/.025 would be amount you would have at the end of 4 years, sitting at time 4 But you want that amount at time ...

*December 10, 2016*

**Business Math ( Future ordinary Annuities)**

Think of it as 48 payments of 1000 at 2.5%, then that sum riding along for 72 periods at 3% plus 72 payments of 1000 for the next 72 periods amount = 1000(1.025^48 - 1)/.025 (1.03)^72 + 1000(1.03^72 - 1)/.03 = 1,009,889.30

*December 10, 2016*

**triangles**

Using the standard notation of listing similar triangles by listing the order of matching vertices, triangle ADE is similar to ABC (i.e. angle A matches with angle A, angle D matches with angle B, angle E matches with angle C, that way all ratios can be easily stated) AE/AD = ...

*December 10, 2016*

**math**

For the first one, the perimeter is 428 cm so each side is 428/4 or 107 cm so its area is 107^2 or 11449 cm^2 Do the second square the same way.

*December 10, 2016*

**alg 2 first final study guide**

f (x) =2X^3 + 2x^2 - 3x + 2 try values of x = ±1, ±2 f(1) = 2 + 2 - 3 + 2 ?0 f(-1) = -2 + 2 + 3 + 2 ? 0 f(2) = 16 + 8 - 6 + 2 ? 0 f(-2) = -16 + 8 + 6 + 2 = 0 , yeahhh x+2 is a factor Using synthetic division I got (x+2)(2x^2 - 2x + 1) = 0 x = -2 or x = (2 ±...

*December 9, 2016*

**Math**

sum(9) = (9/2)(2a + 8d) = 153 times 2 9(2a + 8d) = 306 18a + 72d = 306 divide by 18 a + 4d = 17 term(5) = a+4d = 17 from above

*December 9, 2016*

**Algebra**

the slope of the given line is 5 so the slope of the perpendicular line must be -1/5 So immediately you know your choice is wrong. the new line must be y-3 = (-1/5)(x+10) y = (-1/5)x - 2 + 3 y = (-1/5)x + 1 <-------- C what reasoning do you have to choose A ?

*December 9, 2016*

**Math**

I am not an American, but I was able to Google this and found out the answer in about 2 minutes. Surely you can do that also.

*December 9, 2016*

**Annuities**

amount = 4000( 1.06^30 - 1)/.06 = ....

*December 9, 2016*

**Calculus**

let the equation of the parabola be y = ax^2 , with (-100,100) on it 100 = a(-100)^2 100 = 10,000a a = 100/10000 = 1/100 so y = (1/100)x^2 The car's headlights will hit the point (100,50) when the light-line is tangent to the parabola at the point (a,b) dy/dx = (1/50)x at...

*December 9, 2016*

**Physics. I'd appreciate your help.**

"..acting at 30 degrees" is not clear. Which way does the 30° go, east of north ?, west of north ?, I will solve it as if it was 30° east of north. If not just make the necessary adjustments. the resultant of our two forces, I will consider north to be 90°...

*December 9, 2016*

**precalculus**

We know sinØ = y/r so r sinØ = 2 r(y/r) = 2 y = 2 <------- the horizontal line y = 2

*December 9, 2016*

**math help**

< says "less than" > says "greater than"

*December 9, 2016*

**Algebra**

speed of plane in still air ---- x mph speed of wind ------------ y mph 1575/(x+y) = 7 7x+7y = 1575 x+y = 225 1575(x-y) = 9 9x - 9y = 1575 x - y = 175 add them: 2x = 400 x = 200 back-sub: 200+y = 225 y = 25 state your conclusion

*December 9, 2016*

**Maths**

I will assume that 41/4 is to mean 4 1/4 or 17/4 weight of box C ---- x weight of box B -----(17/4)x weight of box A ---- (5/2)(17/4)x or (75/8)x total weight : 19 5/4 kg or 195/4 kg ??? , the way you typed it. I was going to make the same assumption as above, but why would it...

*December 9, 2016*

**Algebra**

2b + s = 770 ---> s = 770-2b 3b + 2s = 1260 use substitution: 3b + 2(770-2b) = 1260 solve this for b to get burgers sub back into s = ... to get soda

*December 9, 2016*

**Area of a figure**

As you probably noticed, your figure did not come out as you intended. I read that as a rectangle 4 by 10 with an attached triangle of base 6 and height 4 so total area = rectangle + triangle = 4x10 + (1/2)(6x4) = 40 + 12 = 52 btw, "triangular point" makes no sense. ...

*December 9, 2016*

**Algebra**

You don't say what kind of a figure you have, but since you only mentioned three sides, I will assume you have a triangle. middle side ---- x shortest side ---- x-14 longest side ----- x+2 x + x-14 + x+2 = 60 solve for x, sub back into my definitions. Check if your answers...

*December 9, 2016*

**Math solving for x**

4x^2 + 7 is a second degree expression Had it been 4x^3, it would have been a third degree expression. The term with the highest degree determines the degree of the whole expression. If the equation had been 4x^2 + 7 = 0 4x^2 = -7 x^2 = -7/4 which is not a real number, so the ...

*December 9, 2016*

**Math Word Problem**

total number of students on the bus = 46 so what is the percentage equivalent of 20/46 ? You just want an approximation. If it had been 20/50 it would have been 40% you the denominator is a bit less than 50, so your percentage is a bit more than 40%, How about 43% or 44% ?

*December 9, 2016*

**Math Word Problem**

let the amount blueberry juice be x cups let the amount of raspberry cups be 3x cups (notice x : 3x = 1 : 3 , as needed) x + 3x = 48 4x = 48 x = 12 So she needs 12 cups of blueberry and 36 cups of raspberry notice 12 : 36 = 1 : 3 as required.

*December 9, 2016*

**math**

let the angles be 3x, 5x, and 7x you know they have to add up to 180° Solve 3x + 5x + 7x = 180 for x, the sub back into my definitions.

*December 9, 2016*