Friday

October 9, 2015
Total # Posts: 31,225

**math**

don't you get a right-angled triangles with legs of 30 and 60 ? How about Pythagoras ?
*September 30, 2015*

**math**

tile : board = 1/3 ft : 1/2 yds = 4 inches : 18 inches = 2 : 9 area of tile : area of board = 2^2 : 9^2 = 4 : 81
*September 30, 2015*

**TC Maths**

recall that sinxcosx - sinycosy = cos(x+y) LS = (sin^2(x)-cos^2(y))/(Sinx cosx-Sinycosy) notice I inserted the absolutely necessary brackets to make the statement true = (sinx + cosy)(sinx - cosy)/(cos(x+y)) not getting anywhere ≠ tan(x+y) I usually test the equation ...
*September 30, 2015*

**Word problem maths**

Restating what Steve said in a slightly different way: sum of ages of all 21 boys = 21(14 3/12) = 299 1/4 sum of ages without oldest = 20(14 2/12) = 283 1/3 age of boy not included (oldest) = 299 1/4 - 283 1/3 = 15 11/12 which is exactly what Steve did
*September 30, 2015*

**Calculus**

well, let's set the velocity equal to zero ... 3t^2 - 12 = 0 3t^2 = 12 t^2 = 4 t = ± 2, but t ≥0 so the velocity is zero when t = 2 so what is the acceleration when t = 2 ??
*September 29, 2015*

**Algebra I**

Your text or notes should have definitions for a relation and a function In simple terms, a relation is any equation that contains two different variables, usually x's and y's e.g. x + y = 8 is a relation again, in simple terms, if I can isolate the y so it is ...
*September 29, 2015*

**Calculus 1**

well, there you go, how about that
*September 29, 2015*

**Calculus 1**

First of all -9/2x-5/2 is NOT an equation if you meant y = -(9/2)x - 5/2 then by golly, that is what my equation is 9x + 2y = -5 2y = -9x - 5 divide each term by 2 y = (-9/2)x - 5/2 My answer is correct.
*September 29, 2015*

**Calculus 1**

y^2=5x^4-x^2 2y dy/dx = 20x^3 - 2x dy/dx = (20x^3 - 2x)/(2y) = (10x^3 - x)/y at (-1,2) dy/dx = (-10+1)/2 = -9/2 so the tangent equation is 9x + 2y = c with (-1,2) lying on it, so -9 + 4 = c = -5 the tangent equation is 9x + 2y = -5 check: http://www.wolframalpha.com/input/?i=y...
*September 29, 2015*

**Calculus 1**

If it is an astroid, then it should be x^(2/3) +y^(2/3) =4 the way you typed it would result in a circle http://www.wolframalpha.com/input/?i=x%5E2%2F3+%2By%5E2%2F3+%3D4 (2/3)x^(-1/3) + (2/3)y^(-1/3) dy/dx = 0 x^(-1/3) + y^(-1/3) dy/dx = 0 dy/dx = -(x^(-1/3))/y^(-1/3) = -(x/y...
*September 29, 2015*

**math**

Question looks incomplete, but I think I can figure out what you want. Joel's speed --- x Kyle's speed --- x+10 6x + 6(x+10) = 780 solve for x and you got it
*September 29, 2015*

**Indices**

What is all this nonsense? Notice all 3 powers can be expressed as a power with base 2, thus as a power with base 4 P = (64)^-2 = (4^3)^-2 = 4^-6 Q = (1/16)^(1/3) = 16^(-1/3) = (4^2)^-1/3) = 4^(-2/3) R = 8√2 = 2^3(2^(1/2)) = 2^(7/2) = (4^(1/2))^(7/2) = 4^(7/4) the PQR...
*September 29, 2015*

**algebra**

first equation: 2x - 5y = 8 double the 2nd: 2x - 6y = -2 subtract them: y = 10 back into the original 2nd x - 3y = -1 x - 30 = -1 x = 29 x = 29, y = 10
*September 28, 2015*

**Math**

The hundred thousands digit is more than six XX7XX XX8XX XX9XX The thousands digit can be divided by the ones digit and since the number is even, the ones digit is even X47X2 X87X4 X48X2 X88X2 , but all digits are different, so skip the last, so X48X2 X49X2 X89X4 The ten ...
*September 28, 2015*

**math**

Place Shane in the first chair, then the remaining 5 students can be arranged in the 5 chairs in 5! or 120 ways
*September 28, 2015*

**algebra**

anything^0 = 1 , as long as you don't have 0^0
*September 28, 2015*

**Math**

base will be 8-2x by 6-2x height = x volume = x(8-2x)(6-2x) = 192 , where x<3 x(48 - 28x + 4x^2 = 192 4x^3 - 28x^2 + 48x - 192 = 0 x^3 - 7x^2 + 12x - 48 = 0 tried all the "nice" factors of 48, and found no solution. So I let Wolfram graph it and solve it to ge x...
*September 28, 2015*

**math**

see earlier post of the same question
*September 28, 2015*

**math**

increase in the length from 8 to 10 is 2cm percent increase = 2/8 = 25% old area = 40 new area = 70 increase = 30 percent increase = 30/40 = 75% did you realize that the increase will result in a distortion ? The percentage increase of the length is NOT the same as the ...
*September 28, 2015*

**calculus**

1. An amplitude of 1 applies to only the sine or cosine function. the given domain puts the angle in the 2nd quadrant. in that quad, the sine is positive and the cosine is negative, so it has to be y = cosx 2. I know that sin30° = sin(π/6) = 1/2 so csc (π/6) = 2 ...
*September 28, 2015*

**precalc**

there are 3 pairs of cofunctions sine vs cosine tangent vs cotangent secant vs cosecant Surely your text or notes have definitions of the reciprocal functions.
*September 28, 2015*

**Math**

Let's play "I spy" I spy with my little eyes two equal numbers sitting side by side.
*September 28, 2015*

**math**

Damon did this earlier today http://www.jiskha.com/display.cgi?id=1443455187
*September 28, 2015*

**Math**

In 5 hrs the first train went 5(68) or 340 km in the same 5 hrs, the 2nd train went 310 km So what do you think?
*September 28, 2015*

**Math(ANSWERCHECK)!!**

I got 7.159 but perhaps your skills of button-pushing are better than mine
*September 28, 2015*

**MathHELP!**

g(x) factors very nicely to g(x) = (x+1)^2 suppose you write it as g(x) = (x+1)^2 + 0 and you compare it to f(x) = a(x-h)^2 + k, which you must have learned and studied to do this topic
*September 28, 2015*

**math**

since there is a repeat of 117 in the decimal, it is rational. take 117/999 on your calculator your second answer of 32/100 is not in lowest terms as asked for 32/100 = 8/25
*September 28, 2015*

**math**

9. r = d/t multiply each side by t ---> d = rt 10. 3x - y = 10 add y to both sides 3x = y + 10 subtract 10 form both sides 3x - 10 = y strange way of doing equations: here is how I would do the last e.g. P = 2l + 2w P - 2l = 2W -----> I subtracted 2l from both sides P/2...
*September 28, 2015*

**Math Help**

What makes you think so ?
*September 28, 2015*

**Kitondo boys**

(2,2) ---> (-4,-4) (4,2) ---> (-8,-4) (3,4) ---> (-6,-8)
*September 28, 2015*

**Help me! Geometry**

the volume would be proportional to the cube of the linear measurements Since you doubled the 5 cm to 10 cm, the volume would be 2^3 or 8 times as large.
*September 28, 2015*

**Math**

really ?? you were given the hint. What does "sum" mean ?
*September 28, 2015*

**Math**

"If 3 is distributed from a number" What does that mean? Do you mean "subtracted from" ?
*September 28, 2015*

**Math**

girl's share --- x boy's share --- 3x 2(3x) + 3x = 144 etc
*September 28, 2015*

**math**

multi-choice --- x shorts - ----- 20-x x + 3(20-x) = 50 carry 0n
*September 28, 2015*

**Math**

hena --- x rina ---- 3x-100 Add them up and solve for x
*September 28, 2015*

**Math**

3/4 = .75 3/5 = .6 .75x - .6x = 9 .15x = 9 continue
*September 28, 2015*

**Math**

divide both sides by -1.4
*September 28, 2015*

**Math**

btw, your same question was posted by Marie about 5 years ago. I was able to read her post http://www.jiskha.com/display.cgi?id=1287543008
*September 27, 2015*

**Math**

Proofread your post, and retype in proper English
*September 27, 2015*

**Math**

Your post makes absolutely no sense to me. "a height of 12 feet per second " ???? are there two prisms ? Just guessing now: If one prism has a base area of 120 ft^2, and a height of 12 ft, then its volume is 1440 cubic feet if a second prism is 84 inches by 6 ft by ...
*September 27, 2015*

**Math**

Radius of large wheel --- R radius of smaller wheel -- r Circumf of large = 2πR circumf of small = 2πr 2πR - 2πr = 50 R - r = 25/π R = 25/π + r rotations of front wheel = 1440/(2πr) = 720/(πr) rotations of rear wheel = 2400/(2πR) = ...
*September 27, 2015*

**math**

looks good
*September 27, 2015*

**Math**

.8x = 256 x = 256/.8 you didn't post your choices but I bet x is one of them
*September 27, 2015*

**physics**

we have the vector: (35cos325°, 35sin325° x component = 35cos325 = appr 28.670 y component = 35sin 325 = appr -20.075 check: magnitude = √(28.67^2 + (-20.075)^2) = 35 tanØ = -20.075/28.67 = -.700209.. but Ø must be in VI, so Ø = 360-35 = 325
*September 27, 2015*

**math**

Suppose 3 apples cost 1 dollar how much would 54 apples cost? - would you know what to do? I am sure you would vs 3houses take 1 week to frame how long would it take to frame 54 houses ? To me they are the same type of question.
*September 27, 2015*

**algebra**

from the first: y = 9000-x , you had it backwards so .06x + .15(9000-x) = 1215 .06x + 1350 - .15x = 1215 -.09x = -135 x = 1500 then y = 9000-1500 = 7500 You also lost the equal sign in your last 2 lines
*September 27, 2015*

**Math**

I will assume you meant: 8log8(19) If that is the case, then the result is appr 11.328 none of your choices come even close to that. check your typing
*September 27, 2015*

**Math**

the LCD is (x+1)(x-1), so multiply each term by that x(x-1) - 2(x+1) = (x+1)(x-1) x^2 - x - 2x - 2 = x^2 - 1 -3x = 1 x = -1/3
*September 27, 2015*

**Math**

time at 10 mph --- x hrs time at 14 mph --- 5-x hrs since distance = rate x time 10x + 14(5-x) = 68 solve for x
*September 27, 2015*

**Math**

regular price ---- x (2/3)x = 360 x = ....
*September 27, 2015*

**math**

Now: Valeries age --- x Jose's age ------ 78-x 9 years ago: Val ----- x-9 Jo ------ 78-x-9 = 69-x at that time Jose was 3 times as old as Val 69-x = 3(x-9) solve for x
*September 27, 2015*

**shammah int'l school**

magnitude is the length of the hypotenuse of your right-angled triangle. the angle is Ø , such that tanØ = 35/30
*September 27, 2015*

**Math**

What are the choices?
*September 27, 2015*

**Math**

It would go 500!/21 times This is a very "large" number , it would be appr 500 digits long. Considering that 1 Billion has only 10 digits, you can imagine the enormity of this number.
*September 27, 2015*

**Calculus**

A lot of considering taking place here. plane A: direction of given first line = (2,1,4) so that becomes the normal to the plane and its equation must be 2x + y + 4z = C but it passes through (-1,0,2), so -2 + 0 + 8 = C = 6 PLane A: 2x + y + 4z = 6 Plane B: two directions are...
*September 27, 2015*

**math**

Now: Esm ---- x Greg ---- x+2 in 5 years: Esm = x+5 Greg = x+7 form your equation and solve
*September 26, 2015*

**calculus**

the way you typed the domain, which is your choice of x's you could use, is the set of real numbers for both expressions if you meant something like -9/(2+t^2) , since the denominator could never be zero is still the set of real numbers if the 2nd is 1 - 4/(2+t), clearly t...
*September 26, 2015*

**math**

area of rectangle including walk is 29 by 19 area = 551 area of pool = 25(15) = 375 so .....
*September 26, 2015*

**Calculus**

just do what it says ... f(x+h) , if h = .3 = f(x+.3) = 1/(x+.3) so (f(x+h)-f(x))/h = (1/(x+.3) - 1/x)/.3 = ((x - x - .3)/(x(x+.3))/.3 = ( -.3/(x(x-.3) )/.3 = -1/(x(x+.3))
*September 26, 2015*

**Algebra**

The way the question stands, it makes no sense. You would have to drain some of the solution and then add pure antifreeze. does it ask: How much of the current antifreeze, which is 20% , must be drained and the topped up with 100% antifreeze to have a 50% antifreeze ? Please ...
*September 26, 2015*

**lgebra**

your number do not add up to 963 you did not follow my pattern. x + x+1 + x+2 = 963 3x + 3 = 963 3x = 960 x = 320 so the three numbers are 320 , 321, and 322
*September 26, 2015*

**lgebra**

hint: if I told you that the first of 3 consecutive numbers is 17, wouldn't the next two be 18 and 19 ? what did I do to the 17 to get 18? what did I do to the 17 to get 20? if I told you that the first of 3 consecutive numbers is x , what would the next number be ??? let ...
*September 26, 2015*

**ALGEBRA**

width --- w length --- l = w + 4.15 use Ms Sue's formula
*September 26, 2015*

**Proportions**

Assuming the the burning of calories is in a direct proportion to the mass of the person doing the exercise, and since the time frame is the same, 130/194 = 250/x 130x = 48500 x = appr 373 cal's
*September 26, 2015*

**differential calculus**

I would write it as f(t) = 3t^(-1/2) f ' (t) = (-3/2)t^(-3/2) or = -3/(2t√t) just like the original function, the domain is t > 0
*September 26, 2015*

**Math**

Strange equation, I will assume you started with x^2 - 3x + 15.25 = 0 or x^2 - 3x + 61/4 = 0 or 4x^2 - 12x + 61 = 0 from: x^2 - 3x + 61/4 = 0 x^2 - 3x = -61/4 x^2 - 3x + 9/4 = -61/4 + 9/4 (x - 3/2)^2 = -13 x - 3/2 = ±√-13 x = 3/2 ± √-13 you had that, ...
*September 26, 2015*

**Maths word problem need help**

first day -- 1 = 2^0 2nd day -- 2 = 2^1 3rd day -- 4 = 2^2 .. 15th day ---- 2^14 or 16384 accumulate means you want the sum to be 1 million we have a geometric series with a = 1 r = 2 n = ?? sum(n) = 1000000 sum(n) = a(r^n - 1)/(r-1) 1000000 = 1(2^n - 1)/1 2^n = 1000001 take ...
*September 26, 2015*

**Calculus**

let the rate be r 4000(r)(4/52) = 50 r = 50(52)/((4000)(4)) = .165 or 16.5% There are actual companies dealing in paycheck-bridge loans that are charging $10 per week for a $200 quick "paycheck loan" that is a rate of ... 200(r)(1/52) = 10 r = 10(52)/200 = 2.6 or 260%
*September 26, 2015*

**Arithmetic**

let's add 15 hours to 8:00 am, that would put them coming in at 11:00 pm or at 23:00 using standard international units of time but with two sailors you can never tell.
*September 26, 2015*

**Math**

do you mean P( ...., -3/7) ? x^2 + (-3/7)^2 = 1^2 x^2 = 1 - 9/49 = 40/49 x = ±√40/7 = ± 2√10/7 we see that the y is negative, so the point could be in III or IV, thus the ±
*September 26, 2015*

**algebra**

let the daily rental fee be f let the mileage charge be m Jon: 9f + 300m = 315 3f + 100m = 105 Amanda: 5f + 240m = 186 jon x 5 -------> 15f + 500m = 525 Amanda x 3 ---> 15f + 720m = 558 subtract them: 220m = 33 m = 33/220 = 3/20 or .15 back into Jon 3f + 100(.15) = 105 f...
*September 25, 2015*

**mathematics**

given: (a^2 +b^2 +c^2) (x^2 +y^2 +z^2) = (ax +by +cz)^2 a^2x^2 + a^2y^2 + a^2z^2 + b^2x^2 + b^2y^2 + b^2z^2 + c^2x^2 + c^2y^2 + c^2z^2 = a^2x^2 + b^2y^2 + c^2z^2 + 2abxy + 2acxz + 2bcyz a^2y^2 + a^2z^2 + b^2x^2 + b^2z^2 + c^2x^2 + c^2y^2 = 2abxy + 2acxz + 2bcyz now if a:b:c = ...
*September 25, 2015*

**math**

using standard notation, you want cot(43° 41' 13") on my calculator, and most scientific calculators, there is a key labeled D°M'S and recall that cotØ = 1/tanØ so on mine the keystrokes are as follows 1 / tan 43 D°M'S 41 D°M'...
*September 25, 2015*

**pre algebra HELP**

I would write it like this (-12/3)(-8+(-4^2) -6)+2 = -4(-8 -16 -6) + 2 = -4(-30) + 2 = 120+2 = 122 the problem you had is the -4^2 you took it as (-4)^2 (-4)^2 = (-4)(-4) = 16 -4^2 = -1(4)(4) = -16
*September 25, 2015*

**Math**

area = 36 5/6 ft^2 = 221/6 ft^2 width= 5 2/3 ft = 17/3 ft length = area/width = (221/6) / (17/3) = (221/6)(3/17) = 13/2 or 6.5 ft you had that, so clearly it is not long enough to fit the 7 ft table Don't know why you would use 34/6 instead of the 17/3 Whether the table ...
*September 25, 2015*

**interest**

I will assume you have a typo and you meant 5.34% amount = 4720+ 4720(.0534)(9) = ....
*September 25, 2015*

**Calculus**

The rectangle is 2x by 3x with the semicircle on top of the 2x side Since there is a semicircle on top of the rectangle, the area = rectangle + semicircle = basexheight + (1/2)π x^2 = (2x)(3x) + π x^2/2 = 6x^2 + πx^2/2 perimeter = (1/2)(2πx) + 2x + 2(3x...
*September 25, 2015*

**math**

Poorly worded question, since there is no maximum value of y = x^4 - 8x http://www.wolframalpha.com/input/?i=plot+y+%3D+x%5E4+-+8x suppose we blindly proceed as usual ... dy/dx = 4x^3 - 8 = 0 for a max/min 4x^3 = 8 x^3 = 2 x = 2^(1/3) = appr 1.2599 subbing that in gives us y...
*September 25, 2015*

**math**

Intuitively, one should conclude that the sides would be equal, let's prove it let one side by x, then the other is √(144 - x^2) area = (1/2)x√(144-x^2) = (1/2)x(144-x^2)^(1/2) d(area)/dx = (1/2)[ x(1/2)(144-x^2)^(-1/2) (-2x) + (144-x^2)^(1/2) ] = 0 for a max ...
*September 25, 2015*

**P6 maths**

looks like I can't tell Mary and Amy apart.
*September 25, 2015*

**P6 maths**

mary's stamps --- m Amy's stamps ---- a .4m = .75a 40m = 75a m = 75a/40 = 15a/8 after giveaway Mary has .75m Amy has a + .25m a + .25m - .75m = 90 a - .5m = 90 2a - m = 180 2a - 15a/8 = 180 16a - 15a = 1440 a = 1440 m =2700 check my arithmetic
*September 25, 2015*

**Calculus 1**

Here is what your curve looks like http://www.wolframalpha.com/input/?i=plot+y+%3D+%7Cx%7C%2F%28sqrt%285-+x%5E2%29%29 notice that -√5 < x < √5 is our domain, with x = ±√5 as asymptotes Since (2,2) lies in quadrant I I will use y = x/√(5 - x...
*September 25, 2015*

**Math**

Numbers "dividing evenly" has nothing to do with the numbers being even. A number is said to divide into another evenly, if there is a zero remainder after the division. e.g. 15 ÷ 3 = 5 , (note none of the numbers are even) 15 is evenly divisible by 3 but 18 &...
*September 24, 2015*

**Math**

I assume you meant: (3/4) /8 + (1/3) /4 confirm please
*September 24, 2015*

**Solving Linear Equations (Math)**

width ---- x "The length of a rectangle is 5m shorter than three times the width" ---> length = 3x - 5 2x + 2(3x-5) = 46 should be easy to solve, go for it
*September 24, 2015*

**Math**

no 1+1 = 2 , which is not in the set of {0,1}
*September 24, 2015*

**math for managers**

What do you want done ? We are looking at the equation of a straight line
*September 24, 2015*

**Math**

amount at 5% --- x solve for x: .05x + .1(1800-x) = 165
*September 24, 2015*

**math**

prob(correct) = 1/5 prob(not correct) = 4/5 a) to have exactly 5 correct = C(12,5) (1/5)^5 (4/5)^7 = appr .05315 b) prob(2 correct) = C(12,2) (1/5)^2 (4/5)^10 = ... c) 4 or fewer correct ---> 0 correct + 1 correct + 2 correct + 3 correct + 4 correct d) to get 75% he needs ...
*September 24, 2015*

**Calculus**

What method are you using to solve a cubic, since there is no simple "formula" method ? your two answers do not satisfy the equation here is what Wolfram has http://www.wolframalpha.com/input/?i=solve+x%5E3-3x%2B3%3D0 click on "approximate forms" to see one...
*September 24, 2015*

**Algebra 2**

no you were correct at 8/√2 * √2/√2 = 8√2/(√2)^2 , but √2^2 is equal to 2 = 8√2/2 = 4√2 If you have any others, why not check your answer using a calculator e.g. 8/√2 = 5.6568... 4√2 = 5.6568... my answer is correct
*September 24, 2015*

**calculus**

with all due respect what are we doing here ?
*September 24, 2015*

**Math M131A**

end of first bounce it dropped 108 ft during the second bounce it went up and down (1/3) of 108 or 2(1/3)(108) = 72 during the third bounce it went 2(1/3)(72) = 48 during the fourth bounce it went 2(1/3)(48) = 32 so after 4 bounces it went 108+72+48+32 = 260 make a sketch, ...
*September 24, 2015*

**Precalculus**

if x+6 is a factor, then f(-6) must equal zero test if it is
*September 24, 2015*

**Precalculus**

f(x)=2x^2-4x+3 f(x+h) = 2(x+h)^2 - 4(x+h) + 3 = 2(x^2 + 2hx + h^2) - 4x - 4h + 3 = 2x^2 + 4hx + 2h^2 - 4x - 4h + 3 f(x+h)-f(x) = 2x^2 + 4hx + 2h^2 - 4x - 4h + 3 - 2x^2 + 4x - 3 = 4hx + 2h^2 - 4h notice all the "non-h" terms dropped out. This MUST always happen. If ...
*September 24, 2015*

**maths**

I think he means 1 1/2 m and 1 1/3 m - Usually we leave a space between the numbers in mixed fractions - Secondly, in the metric system we would not use such a fraction, it would be either 1.5 m or 150 cm Height of human is expressed in cm in the metric system. - Thirdly, &...
*September 24, 2015*

**Precalculus**

i -3
*September 24, 2015*

**Maths**

speed = distance/time = 7.5 km / 27.5 min = 7500 m / (27.5*60) seconds = 50/11 m/s
*September 24, 2015*

**MATH (vector addition)**

my diagram consists of a right-angled triangle with a hypotenuse of 4, a height of 2 and a horizontal of x by Pythagoras, x^2 + 2^2 = 4^2 x = 2√3 , his actual swimming speed direction: sinØ = 2/4 Ø = 30°
*September 24, 2015*