Sunday

January 22, 2017
Total # Posts: 37,359

**Mathmatics help please**

clearly 25 and 15

*November 26, 2016*

**Maths help asap please**

3c-7 > 5c+4 3c - 5c > 4+7 -2c > 11 c < -11/2 or c < -5.5 so the smallest integer that is a solution is c = -6 check: if c = -6, -18 - 7 > -30+4 -25 > -36 , true! if c = -5 -15-7> -25+4 -22 > -21 , false

*November 26, 2016*

**Math**

subtract 2 from each part, and you are done -3<x+2<3 -3-2 < x+2-2 < 3-2 -5 < x < 1 ---> ( x lies between -5 and 1 )

*November 26, 2016*

**Math**

nothing wrong with that you could just use the trig-vector notation resultant = (10cos60,10sin60) + (20cos120,20sin120) + (30cos180,30sin180) + (40cos270,sin270) = (5, 5?3) + (-10, 10?3) + (-30, 0) + (0, -40) = ( -35, 5?3-40 )) your sketch will confirm that

*November 26, 2016*

**Trigonometry**

Both Steve and I both told you what was wrong with the wording of the question. http://www.jiskha.com/display.cgi?id=1480115359 Did you even look at the responses?

*November 25, 2016*

**Math**

(2 x 3)>2 - 5>2 is a false statement. you are basically saying: 6 > 2-5 > 2 6 > -3 > 2 the part 6 > -3 is true, but -3 > 2 is nonsense To ask "evaluate" the expression makes no sense Hey, wait a minute! Did you mean (2 x 3)^2 - 5^2 ?? then you...

*November 25, 2016*

**math**

You can't just drop the variable. 5(2x + 7) = 10x + 35 Now you can see that we can't add the 10 and 35 since they are "unlike" terms

*November 25, 2016*

**Math**

correct

*November 25, 2016*

**math**

The 14M, the 3M and the 1M are all expenses so what is 20 - (14+3+1) ?? I get 2 Million

*November 25, 2016*

**Calculus AB**

3y^3 + 2x^2 = 5 9y^2 dy/dx + 4x = 0 dy/dx = -4x/9y^2 when y = 1 , 3 + 2x^2 = 5 2x^2 = 2 x = ± 1 , but in quadrant 1, x = 1 dy/dx = -4(1)/9 = -4/9 equation of tangent: y-1 = (-4/9)(x-1) 9y-9 = -4x + 4 4x + 9y = 13 check: http://www.wolframalpha.com/input/?i=plot+3y%5E3+%...

*November 25, 2016*

**Trigonometry**

y = cos(3?/4 - x) already is a single function of x, namely the cosine function. I don't understand what else you want to do with it. We know: using cos(A-B) = cosAcosB + sinAsinB cos(3?/4 - x) = cos 3?/4 cosx + sin 3?/4 sin x = -?2/2 cosx + ?2/2sinx = ?2/2 (sinx - cosx...

*November 25, 2016*

**Math**

In the original number let the unit place by x then the tens place is 2x, (obviously x < 5) then the number in terms of its value is 10(2x) + x and the number reversed is 10x + 2x the difference between these two is 36, just translate this into Math. 10(2x) + x - (10x + 2x...

*November 25, 2016*

**Math**

clearly the 5 has to go in the unit position for the number to be odd At the front, what would be bigger, something 6 hundred or something 8 hundred?

*November 25, 2016*

**Mathematics**

let his sales be x .06x + 6000 = 10200 solve for x

*November 25, 2016*

**Maths**

330/x - 330/(x+5) = 1/2 That's ok, we end up with a quadratic. Multiply each term by 2x(x+5) 660(x+5) - 660x = x(x+5) 660x + 3300 - 660x = x^2 + 5x x^2 + 5x - 3300 = 0 (x-55)(x+60) = 0 x = 55 or x = -60, we would reject the -60 So your inward speed is 55 km/h, the return ...

*November 25, 2016*

**math**

90 = 2x3x3x5 since each pair of equal factors produces a perfect square, we have 3x3, a perfect square. So all we need is another 2 and another 5 How about 2x2x3x3x5x5 = 900 900 = 30^2 , so it is a perfect square, and it is divisible by 90

*November 24, 2016*

**math-factors and multiples**

both 40 and 32 divide by 8 both a^3 and a^2 divide by a^2 The GCF is 8a^2

*November 24, 2016*

**math**

It is 30a^2

*November 24, 2016*

**math**

5 ? m/-3 + 18 add m/3 to both sides 5 + m/3 ? 18 m/3 ? 13 m ? 39 or 5 ? m/-3 + 18 -13 ? m/-3 times -3 39 ? m m ? 39 , same as above

*November 24, 2016*

**math**

the slope of the 2nd is -2/16 = -1/8 which is the negative reciprocal of the slope of the first. Thus, the lines are perpendicular.

*November 24, 2016*

**math**

I assume we are factoring 25m^6-121m^4 = (5m^3 - 11m^2)(5m^3 + 11m^2)

*November 24, 2016*

**Calculus applications**

let the height be 100 cm^3 ?r^2 h = 100 h = 100/(?r^2) S = 2 circles + the sleeve = 2?r^2 + 2?rh = 2?r^2 + 2?r(100/(?r^2)) = 2?r^2 + 200/r you typed it wrong, it should have been 2?r^2 + 200 r^-1 dS/dr = 4?r - 200/r^2 = 0 for a min of S 4?r = 200/r^2 r^3 = 200/(4?) = 25/? r...

*November 24, 2016*

**Math**

Now: Marcus ---- x John ------ x+10 5 years from now: John's age = x+15 5 years ago: Marcus = x-5 3(x+15) = x-5 that would give you the silly answer of x = -25 checking now Marcus is -25 John is -15 5 years from now, John is -10 and 5 years ago Marcus was -30 sure enough 3...

*November 24, 2016*

**maths**

Without any restrictions, number of committees = C(10,4) = 210 include at least one woman ---> exclude cases of all 4 being men number of ways = 210 - C(5,4) = 205

*November 24, 2016*

**math**

now: daughter ---- x years Mary -------- 3x years 4 years ago: daughter : x-4 Mary : 3x-4 (x-4)(3x-4) = 40 3x^2 -16x + 16 = 40 3x^2 - 16x - 24 = 0 I was expecting it to factor, hoping for whole number solution, but .... x = (16 ± ?544)/6 = 6.55 or a negative check: if ...

*November 24, 2016*

**Math**

let the two numbers be 9x and 3x then 9x + 3x = 72 .. x = 6 sub into my definition to get the numbers.

*November 24, 2016*

**Math**

Find the midpoint of AB, then use your "distance between two points" formula to get CM .

*November 24, 2016*

**Maths**

let the numbers be x and x+1 solve: x + x+1 = 39

*November 24, 2016*

**math**

your first equation should have been 4x +5 = 37 instead of 4x(5) = 37 but then you miraculously switched it to the right one as you solved it. The answer is correct

*November 24, 2016*

**Further mathematics**

x^2 + y^2 = 5xy complet the square: x^2 + 2xy + y^2 = 7xy (x+y)^2 = 7xy take log of both sides 2log(x+y) = log 7 + logx + logy 2log(x+y) - log7 = logx + logy 2log(x+y) - 2log 7^(1/2) = logx + logy 2[ log(x+y) - log ?7] = logx + logy 2 log( (x+y)/?7 ) = logx + logx as required ...

*November 23, 2016*

**algebra~help me**

18^(4-4y)=54(?2)^(3y-2) take log of both sides (4-4y)log18 = lof54 + (1/2)(3y-2)log2 4log18 - 4ylog18 = log54 + (3y/2)log2 - log2 4log18 - log54 + log2 = y( (3/2)log2 + 4log18) 3.58972... = (5.4726...) y y = .655941

*November 23, 2016*

**Calculus**

so considering t = 0 to correspond with 2016 1000 = A 3^0 , but 3^0 = 1 A = 1000 b) y(5) = 1000 3^(4/3) = .... Use your calculator c) 100000 = 1000 3^(t/4) 1000 = 3^(t/4 take log of both sides log 1000 = log 3^(t/4) 3 = (t/4)log 3 t/4 = 3/log3 t = 12/log3 = appr 25.15 years iv...

*November 23, 2016*

**math**

Assuming the farm is a rectangle ... length --- x width = 39 2x + 2(39) = 187.2 find x once you have x, take x/39

*November 23, 2016*

**algebra**

How about you showing me some of your steps, now that I have done two very similar to this one for you ?

*November 23, 2016*

**algebra**

breath (width) ---- x length -----------x+12 2x + 2(x+12) = 144 carry on

*November 23, 2016*

**algebra**

smaller --- x larger --- y Now just translate into Math. 3(y - x) = y+3 3y - 3x = y+3 3x - 2y = -3 ** 3(y+x) = 8x + 2 3y + 3x = 8x + 2 5x - 3y = 2 *** solve ** and *** You should get two whole numbers.

*November 23, 2016*

**Differential calculus**

If expanded you would get a standard cubic Its x-intercept are (2,0), (-1,0) and (-3,0) http://www.wolframalpha.com/input/?i=plot+y%3D(x-2)(x%2B1)(x%2B3)

*November 23, 2016*

**maths**

let the two numbers be 5x and 7x "it's lam is 210" , I have no clue what that means.

*November 23, 2016*

**maths**

I will assume you meant the ninetieth term. If a and d are the first term and common difference respectively, then term(90) = 30 a + 89d = 30 a = 30-89d sum(17) = (17/2)(2a + 16d) = (17/2)(2(30-89d) + 16d) = (17/2)(60 - 162d)

*November 23, 2016*

**Math**

Did you make a sketch? 1) sin30° = h/15 h = 15sin30 = 15(1/2) = 7.5 m Very unsafe way to place a ladder, the angle should be > 76° at the ground 2) in reference to the 60° angle, the 13 m is the "adjacent" and you want the "opposite" side ...

*November 22, 2016*

**Statistics**

numer of ways = 15 x 14 x 12 = .... (assuming the order matters, and you have specified positions)

*November 22, 2016*

**Math**

correct (the jet stream does not just flow over the US )

*November 22, 2016*

**I dont know**

they can be any (x,y) such that x^2 + y^2 = 64 e.g. (2 , ?60), (?39 , 5) , (8,0), (8,0), (4?2 , 4?2) etc

*November 22, 2016*

**Algebra2**

but log8 2 = 1/3 so log8 (a/2) = log8 a - 1/3

*November 22, 2016*

**math**

equilateral ---> all sides are equal, so 3x+2 = 2y-x 4x + 2 = 2y 2x + 1 = y also 3x+2 = y + 3 3x+2 = 2x+1 + 3 x = 2 then y = 5 so each side is 3x+2 = 8 and the perimeter is 24

*November 22, 2016*

**Math**

9/(2x) = 15/12 "cross-multiply" 30x = 108 x = 108/30 = 18/5 or 3.6

*November 22, 2016*

**Math**

amount of peaches --- x lbs amount of melons ---- y lbs amount of apples ----- 100 - x - y lbs (assume both x and y are whole numbers) 10x + 3.5y + .5(100-x-y) = 100 double every term 20x + 7y + 100 - x - y = 200 19x + 6y = 100 x = (100 - 6y)/19 , clearly 0 < y < 6 by ...

*November 22, 2016*

**10th Grade Math**

To have a triangle, the sum of any two sides must be greater than the third side. look at C 5+10< 18 all the others form a triangle

*November 22, 2016*

**maths**

The volume of 2 similar objects is proportional to the cube of its linear sides 320/x = 8^3/6^3 512x = 69120 x = 69120/512 = 135 or the side ratio is 6/8 = 3/4 old volume = 8(l)(w) = 320 lw = 40 new volume = 6(3l/4)(3w/4) = 54/16 lw = (54/16)(40) = 135

*November 22, 2016*

**maths**

surface area of smaller = 4? r^2 surface area of larger = 4?(3r)^2 = 36?r^2 which is 9 times as great or the area of similar objects is proportional to the square of their linear dimension, so 1^2 : 3^2 = 1 : 9

*November 22, 2016*

**Algerbra**

so it will differ only in the constant let the equation be y = -4x + b but (-8,-4) lies on it, so -8 = -4(-8) + b solve for b and write the equation.

*November 22, 2016*

**Trigonometry**

tanØ = 4/1 = 4 Ø = 75.96 The angle should be 76° by ratio: 4/1 = 16/x x = 4

*November 22, 2016*

**Math**

number of adult tickets sold = 3x number of children tickets sold = 5x 5x = 3x + 180 take over.

*November 22, 2016*

**math**

LCD is 5b a/5 +4/b = ab/5b + 20/5b = (ab + 20)/(5b)

*November 22, 2016*

**Algebra**

slope of main street = (33-17)/(-22+2) = -4/5 so slope of Grimes Blvd = +5/4 y - 9 = (5/4)(x-80) y = (5/4)x - 100+ 9 y = (5/4)x - 91

*November 22, 2016*

**Math**

Follow the same steps I just showed you in your previous problem.

*November 22, 2016*

**Math**

number of girls ---- 7x number of boys ---- 5x "there are 8 more girls 10 boys" makes no sense are you saying, "there are 8 more girls than boys" ? which translated into math would be 7x = 5x+8 take it from here

*November 22, 2016*

**maths**

done, see below

*November 22, 2016*

**algebra**

number of nickels ---- x number of dimes ----- x+10 number of quarters = 37-(x + x+10) = 27 - 2x value of coins = 5x + 10(x+10) + 25(27-2x) = 5x + 10x + 100 + 675 - 50x = 775 - 35 x

*November 22, 2016*

**Math**

I don't know, you did not state the rate of interest.

*November 22, 2016*

**maths**

volume of wooden rod = ?(2^2)(6) = 24? volume which is submerged = 12? So the volume in the cylinder will change by that amount ?(4^2)h = 12? 16h = 12 h = 12/16 cm = 3/4 cm new depth = 4+3/4 cm = 19/4 cm or 4.75 cm

*November 22, 2016*

**maths**

" ... is placed in the tin or floats exactly half 2.what is the New depth of water " Retype in proper English so I can understand it.

*November 22, 2016*

**maths**

OK, even though have always been told that we can't add apples and oranges, ..... let the amount of apples be x lbs amount of oranges ----- (52 - x) lbs 5.25x + 3.8(52-x) = 4.25(52) 5.25x + 197.6 - 3.8x = 221 1.45x = 23.4 x = 16.1 lbs of apples and 35.9 lbs of oranges appr...

*November 22, 2016*

**math**

cost = 7.2(12) = 86.4 18 eggs = 1.5 dozen so you sold 10.5 dozen at 7.5 return = 10.5(7.5) = 78.75 loss = 86.4 - 78.75 = 7.65

*November 22, 2016*

**Maths**

Four times as much, or 32 kg Can you show me why that is so?

*November 22, 2016*

**maths**

volume of ball = (4/3)?(4.5)^3 So that is the change in volume in the cylinder once removed ?(6^2) h = (4/3)?(9/2)^3 36h = (4/3)(729/8) = 243/2 h = 243/72 = 27/8 the water will fall 27/8 cm or 3.375 cm check my arithmetic.

*November 22, 2016*

**Algebra 1**

The boat will be .15 miles from Ellen coming and going away. So 1 - 70t = .15 OR -1 + 70t = .15 t = .01214... hrs or t = .01642.. hrs t = .01214(3600) sec or t = .01642(3600) sec t = 43.7 sec OR t = 59.1 sec

*November 22, 2016*

**check - Math**

ok, the cat's were adopted, that means the count was reduced by 120, not increased. I read the question incorrectly number of cats after adoption = 2x - 120 make the simple change in the equation and solve

*November 22, 2016*

**Math**

number of cats ---- 2x number of dogs ----3x after adoption: number of cats = 2x + 120 (2x+120) : 3x = 3 : 7 (2x+120)/(3x) = 3/7 14x + 840 = 9x 5x = -840 x is a negative, which is not possible. notice 2:3 = .66.. and 3:7 = .42 , which is < 2/3 How can the ratio of cats : ...

*November 22, 2016*

**maths**

Area of a triangle = (1/2)(ab)sinØ where a and b are sides with Ø as the angle between them. Your data is perfectly suited for that formula

*November 22, 2016*

**found my error - Go with Steve - maths need help**

The second equation had addition, I read it as another subtraction.

*November 22, 2016*

**maths need help**

Log (a+3) (base 9) - log b(base 9)= c + (1/2) log9 (a+3) - log9 b = c+1/2 log9 ((a+3)/b) = c+1/2 ---> 9^(c+1/2) = (a+3)/b 3^(2c+1) = (a+3)/b ** log (a-3) (base 3) + log b (base 3)=c - 1 log3 (a-3)+ log3 b = c-1 log3 ( (a-3)/b )= c-1 --> 3^(c-1) = (a-3)/b *** divide ** by...

*November 22, 2016*

**Math**

let the roots of ax^2+bx+c=0 be m and n then m:n = r:1 m/n =r/1 m = rn sum of roots = m+n = rn + n = n(r+1) = -b/a ** product of roots = mn = n^2 r = c/a *** divide ** by *** (r+1)/nr = (-b/a) / (c/a) = -b/c rc + c = -bnr rc + bnr = -c r(c + bn) = -c r = -c/(c+bn) For acr^2+(...

*November 21, 2016*

**math**

A standard rotation is 2?. So whatever angle you have either adding or subracting multiples of 2? will yield a coterminal angle. e.g 8?/3 -----> think 480° 8?/2 - 2? = 2?/3 -----> think 120° 8?/3 + 2? = 14?/3 -----> think 840° 8?/3 - 4? = -4?/3 -----> ...

*November 21, 2016*

**calculus**

c(x)=3x^3 - 12x^2 +9000x c ' (x) = 9x^2 - 24x + 9000 = 0 for a max/min of c(x) 9x^2 - 24x + 9000 = 0 This equation has no real solution. c(0) = 0, for all values of x > 0, c(x) increases so our minimum cost is when we don't produce anything, (that actually makes ...

*November 21, 2016*

**Math**

If you are referring to your previous post, look at my reply to it.

*November 21, 2016*

**Math**

For any number to be divisible by 6, it must be divisible by both 2 and 3 To be divisible by 2, the unit digit must be even or zero, so that eliminates A - 5. To be divisible by 3, the sum of the digits must be a multiple of 3 (divisible by 3) Since we have a sum of 8 for the ...

*November 21, 2016*

**Algegra**

So let's just change Ax + By = C to the form y = mx + b Ax + By = C By = -Ax + C divide each term by B y = (-A/B)x + C/B So compare that to y = mx + b m = -A/B so I have just developed a quick way to find the slope of any equation in general form e.g. 7x + 9y = 17 has slpe...

*November 21, 2016*

**Math**

so with her new test, there will be 6 tests (sum of what you have so far + x)/6 = 69 solve for x

*November 21, 2016*

**maths**

original fraction --- x/y first new fraction: (x+1)/(y+1) = 2/3 3x + 3 = 2y + 2 3x - 2y = -1 ** second new fraction: (x-2)/(y-2) = 3/5 5x - 10 = 3y - 6 5x - 3y = 4 *** solve the two equations ** and ***

*November 21, 2016*

**mathematical methods for economics**

Did you try Venn diagrams? Start filling in from the intersection of all three circles. Put 50 in that intersection, then work your way outwards from there.

*November 21, 2016*

**Math, Surds**

let the length of each side be s s^2 = 60 s = ?60 = ?4*?15 = 2?15 each side is 2?15 m perimeter = 8?15 m

*November 21, 2016*

**Mathss**

If you have a right-angled triangle, the area is (1/2) base x height You have the base and height, clearly 65 will not be used since it is the hypotenuse. So go for it. For the second, if you have two sides and the contained angle, then the area is (1/2)(a)(b)sinØ, ...

*November 21, 2016*

**maths**

The first two triangles are clearly right-angled. Is the third one ? is 65^2 = 33^2 + 56^2 ??, YES So make sketches of each one. for a) I labeled by triangle ABC, where a = 30 angle A = 90, and angle B = 30° sin35° = 30/b bsin35 = 30 b = 30/sin35 = appr 52.30 tan35 = ...

*November 21, 2016*

**MATHS**

All of the trig ratios shown are based on "standard" angles. We used to have math kits that contained a compass, a protractor and two triangles. One had angles 45-45-90°, the other had 30-60-90° The ratio of sides of the 30-60-90 were 1 : ?3 : 2 and for the ...

*November 21, 2016*

**Math probability**

prob(big winner) = 1/C(68,5) = 1 / 10,424,128 = appr .000,000,1

*November 20, 2016*

**algebra**

first number ---- x second number --- x+9 third number ----- 82 - x - x - 9 = 72 -2x all three numbers are expressed in terms of one variable: x , x+9, and 72-2x

*November 20, 2016*

**algebra 1**

just subtract them: 10y = -10 y = -1 plug that into the first: -4x + 7(-1) = -3 -4x = -3+7 = 4 x = -1 x = -1, and y = -1

*November 20, 2016*

**Math**

There are no "points in the table below"

*November 20, 2016*

**Math**

y+x =10 y - x = 20 add them: 2y = 30 y = 15 15+x = 10 x = -5 x = -5, y = 15

*November 20, 2016*

**Life Science Math**

acceleration --- a then v = at + c at the start, t = 0, and v=0 0 = 0 + c ---> c = 0 so v = at when t = 3 sec = 3/3600 hrs or 1/1200, v = 60 60 = a(1/1200) a = 72000 ------> v = 72000t if s is the distance travelled , s = 36000t^2 + k when t = 0 , s = 0, so k = 0 s = ...

*November 20, 2016*

**f math**

I will assume that by t ta you mean Ø so sin(90 - 5Ø) = cos(180 - Ø) but sin(90 - 5Ø) = cos Ø just like sin(90 - 30) = cos30 so we have cos(5Ø) = cos(180-Ø) take arccos of both sides 5Ø = 180-Ø 6Ø = 180 &...

*November 20, 2016*

**f math**

What is "t ta" ?? Where does "d" enter the picture?

*November 20, 2016*

**Math**

agree with C I did not answer the question that was asked My 4 slices would represent 1/2 of an 8 slice pizza.

*November 20, 2016*

**Math**

If each pizza is cut into 8 slices, then in the 7 pizzas there are 56 slices So each of the 14 student would get 56/14 or 4 slices. You did not post any "answer choices", so I hope 4 is in there.

*November 20, 2016*

**Math**

let one number be x let the other be x+7 x + x+7 = 63 solve for x, and all that is unknown shall be revealed.

*November 20, 2016*

**Math**

Done the way you typed it: |1-15x/5| < 3 1 - 15x/5 < 3 AND -1 + 15x/5 < 3 -3x < 2 AND 3x < 4 x > -2/3 AND x < 4/3 What you probably meant: | (1-15x)/5 | < 3 (1 - 15x)/5 < 3 AND (-1 + 15x)/5 < 3 1 - 15x < 15 AND -1 + 15x < 15 -15x < 14 AND...

*November 20, 2016*

**Math Quadratic Equations . URGENT!!!!**

look back when you posted this earlier

*November 20, 2016*

**Trig**

Did you make a sketch? I followed your labels and let the base of the building be B in triangle DAB, tan30 = DB/30 DB = 30tan30° = ... in triangle CAB, tan 60 = CB/30 CB = 30tan60 = ... CD = CB - DB = ....

*November 20, 2016*

**Math**

correct, ***80 is the only one divisible by 4

*November 20, 2016*