Thursday

May 5, 2016
Total # Posts: 34,509

**Algebra**

let the width of the page be x inches and its length be y inches 2(x+y) = 42 x+y = 21 y = 21-x width of printed area = x-3 length of printed area = y-2 area = (x-3)(y-2) = (x-3)(21-x - 2) = (x-3)(19-x) = -x^2 + 22x - 57 d(area)/dx = -2x + 22 = 0 for a max of area 2x=22 x = 11 ...
*February 22, 2016*

**Math**

what is 64(.4) ?
*February 22, 2016*

**MATHS**

recap: x+y+z = 1 x^2 + y^2 + z^2 = 35 x^3 + y^3 + z^3 = 96 let's just take (x+y+z)^2 (x+y+z)^2 = x^2 + y^2 + z^2 + 2xy + 2xz + 2yz 1 = 35 + 2(xy+xz+yz) xy + xz + yz = -34/2 = -17 *** let's cube x+y+z=1 (x+y+z)^3 = x^3+y^3+z^3 + 3x^2(y+z) + 3y^2(x+z) + 3z^2(x+y) 1 = 96...
*February 22, 2016*

**Algebra**

grade7: 7girls, 5 boys grade8: 4 girls, 4boys prob(boy from gr7 and boy from gr8) = (5/12)(4/8) = 5/24
*February 22, 2016*

**Math**

If the interest rate is stated per year, as in 15% per annum, then use years for your T If the interest rate is stated as a rate per month, then use months for your T. I would think that the 15% is an annual rate , so use 2 , not 24.
*February 22, 2016*

**Math**

Something is not right here. If P divides AB in a certain ratio, then P must lie on AB. It does not. (back to basics: slope AP = 2/4 = 1/2 slope of PB = 0/10 = 0 ) Your wording of your sentence is befuddled. check your typing, or else the question makes no sense
*February 22, 2016*

**Math**

Christy ---- x Lina -------x+4 Five years from now: Lina -------x + 9 Four years ago: Christy --- x-4 x+9 = 2(x-4) x+9 = 2x - 8 x = 17 Christy is 17 and Lina is 21 check: five years from now Lina 26 Four years ago Christy was 13 is Lina age twice that of Christy ? YES
*February 22, 2016*

**oblique triangle**

I don't think so, AB/sinC = 12.57/sinB AB = 12.57sin54.23/sin68.41
*February 22, 2016*

**oblique triangle**

Here is a little trick if your calculator has a key looking something like D°M'S you can key in the traditional "degree-minute-second" notation directly and do arithmetic e.g to enter B = 68°24'36" press 68 D°M'S 24D°M'S 36 = it ...
*February 22, 2016*

**Math**

The centroid is located 2/3 of the length of a median, measured from the vertex OA = (3, -2) OD = (-3, -4) we know AG : GD = 2 : 1 OG =(1/3)(3,-2) + (2/3)(-3,-4) = (1, -2/3) + (-2, -8,3) = (-1, -10/3) or -i - (10/3)j
*February 22, 2016*

**trigonometry**

tan 30.75° = 42/x , x is the horizontal distance x = 42/tan30.75 = ....
*February 22, 2016*

**Math**

b) let's look at A(x) = 2x^2 - 20x + 100 This is an upwards parabola. I will assume you know how to find its vertex. In standard form you would get A(x) = 2(x-5)^2 + 50 with vertex at (5,50) This means your smallest inner square has an area of 50 square units when x = 5, ...
*February 22, 2016*

**Maths**

solving as a proportion: v = kt for the given: 49 = k*5 k = 9.8 so v = 9.8t when t = 8 v = 9.8*8 = 78.4 or , as a simple ratio v1/v2 = t1/2 49/t2 = 5/8 5t2 = 49*8 t2 = 49*8/5 = 78.4
*February 22, 2016*

**Math**

interest on first loan = 800*.075*2 = 120 so the interest on the second loan = 138-120 = 18 using the simple interest formula: 18 = P*.03*2 P = $300
*February 22, 2016*

**Calculus**

why not doing it the actual way ???? ∫ ln(t^2) dt = t ln(t^2) - 2t | from ?????? you have a = 1 to b = 3x are a and b the lower and upper values ? if so, = 3x ln (9x^2) - 6x - (0 - 2) = .....
*February 21, 2016*

**Algebra**

amount of the $5.00 tea ---- x pounds amount of the $3.00 tea ---- 80-x solve for x 5x + 3(80-x) = 80(3.75)
*February 21, 2016*

**algebra**

i = .08/4 = .02 P( 1 - 1.02^-12)/.02 = 2000 solve for P
*February 21, 2016*

**Calculus**

since v(t) = sin (2t) then s(t) = -(1/2)cos(2t) + c , where s(t) is the distance when t = 0, s(0) = -(1/2)cos 0 + c = c - 1/2 when t = π s(π) = -(1/2)cos 2π + c = c - 1/2 distance traveled = s(π) - s(0) = c - 1/2 - (c - 1/2) = 0 which is exactly what you ...
*February 21, 2016*

**math**

use rules of logs ln(x+4)+ln(x−4)=0 , x > 4 ln( (x+4)(x-4) ) = 0 e^0 = (x+4)(x-4) 1 =x^2 - 16 x^2 = 17 x = ±√17 , but x > 4 so x = √17
*February 21, 2016*

**Math**

poorly worded question: the original piece could be an infinite number of dimensions, e.g. 2/3 by 4/3 or 1/3 by 8/3 or 1.25/3 by 6.4/3 or √8/3 by √8/3 or .... similarly, we are not given the dimensions of the cut-off piece only its area it could be 1/3 by 2/3 or 1....
*February 21, 2016*

**Algebra**

the key word is "dropped" If you drop something, the initial velocity is zero
*February 21, 2016*

**Math**

I have now answered several of your questions You have not shown any steps or signs that you understand these problems. Questions a) - f) are just terms that are found right in the question. from g) on they follow the same type as your other problems. you try it. Let me know ...
*February 21, 2016*

**Math**

I will assume that the rates are per annum compounded monthly Choice #1: i = .05/12 , n = 36 P(1 - 1.0041666..^-36)/.0041666..=20000 P = 599.42 ---- can't afford that Choice #2 i = .06/12 , n = 48 P(1 - 1.005^-48)/.005 = 20000 P = 469.70 ---- still can't afford it ...
*February 21, 2016*

**Math**

a) P( 1 - (1+.09/12)^-120)/(.09/12) = 10500 P( 1 - 1.0075^-120)/.0075 = 10500 P = 133.01 b) - d) are actually bogus questions. Since you would be adding values of money that are not in the same "time spot" the result would be invalid. The actual answer to "What ...
*February 21, 2016*

**math**

this can be reduced to two cases, actually 4, but 2 are duplicates + -- + + -- - - -- + - -- - 3y+7 = 2y-1 or 3y+7 = -2y + 1 y = -8 or 5y = -6 y = -8 or y = -6/5
*February 21, 2016*

**Math**

two cases to start: x^2 - 6x = 9 or -x^2 + 6x = 9 #1: x^2 - 6x - 9 = 0 two solutions #2: x^2 - 6x + 9 = 0 (x-3)^2 = 0 x = 3 so there are 3 solutions. You asked "how many"
*February 21, 2016*

**maths -partial fractions**

from Steve's line of A(x+3)(x^2+3) + B(x^2+3) + (Cx+D)(x+3)^2 = x^2+15 since this is an identify, thus valid for all values of x, pick some values that eliminate some of the terms, or makes calculations easy e.g. let x = -3 0 + 12B + 0 = 24 B = 2 * let x = 0 9A + 3B + 9D...
*February 21, 2016*

**Math**

"as shown below" does not work here, but I have seen that problem many many times. ok so far as your 3x + 2y = 100, assuming you defined y as the length and x as each of the dividing widths. from that y = (100-3x)/2 = 50 - (3/2)x I object to your wording of "...
*February 21, 2016*

**LOGS**

Your E's are confusing. And what about that E0 = 10-12wattsm2 ??
*February 21, 2016*

**math**

W = k(1/L) given: if L = 4m, W = 1000 kg 1000 = k(1/4) k = 4000 so : W = 4000/L if L = 17 W = 4000/17 = appr 235.29 kg or by ratio: W1/W2 = L2/L1 1000/W2 = 17/4 17W2 = 4000 W2 = 4000/17 = 235.29 , as before
*February 21, 2016*

**math**

height ---- x length ---- x+14 x^2 + (x+14)^2 = 26^2 2x^2 + 28x + 196 = 676 x^2 + 14x = 240 completing the square ... x^2 + 14x + 49 = 240+49 (x+7)^2 = 289 x+7 = √289 = 17 x = 10 the TV is 10 inches by 24 inches (odd size) check: 10^2 + 24^2 = 100 + 576 = 676 = 26^2 My ...
*February 21, 2016*

**math**

Just translate ... d = k(r^2) , where k is a constant plug in the given to find k 100/5280 = k(1600) k = (100/1600)/(5280) = 1/84480 so your formula is d = (1/84480)r^2 if d = 256 ... 256/5280 = (1/84480)r^2 84480(256)/5280 = r^2 256(16) = r^2 r =16(4) = 64 mph notice we could...
*February 21, 2016*

**Trig Identities**

both sin^2 x and cos^2 x are not easy to integrate. but we know that cos (2x) = cos^2 x - sin^2 x or = 2cos^2 x - 1 or 1 - 2sin^2 x you should have those available to you so taking 2cos^2 x - 1 = cos (2x) 2cos^2 x = cos (2x) + 1 cos^2 x = (cos(2x) + 1/2 = (1/2)cos(2x) + 1/2 ...
*February 21, 2016*

**Mindy/Carol - Algebra**

Please don't switch names
*February 21, 2016*

**Math**

you forgot the fact that there could have been a constant in front of the whole mess. I also used (2x-1) instead of (x - 1/2) let y = a(2x-1)(x-1)(x-(x-(3+2i))(x - (3-2i)) = a(2x - 1)(x-1)(x - 3 - 2i)(x - 3 + 2i ) If you expand the last two, you get x^2 - 6x + 13 so ... y = a(...
*February 21, 2016*

**maths**

so we want 1 year at 13% and 3 years at 8% value at end of 4 years = 45000(.87) (.92)^3 = $30,485.64
*February 21, 2016*

**geometry**

yes, 11.7 is correct to the nearest tenth
*February 21, 2016*

**math**

why not just add them up? 2(x-1)-4(x-1) = -2(x-1)
*February 21, 2016*

**maths**

250+12n=670 12n=420 n =35
*February 21, 2016*

**maths**

a+7d = 37 a+4d - (a+11d) = 15 -5d = 15 d = -3 into the first: a - 21 = 37 a = 58 sum(15) = (15/2)(116 + 14(-3)) = 555
*February 21, 2016*

**Math**

in the solution of tanØ = 0 I should have included Ø = 180° so Ø = 0°, 135°, 180°, 315°
*February 21, 2016*

**Math**

recall that sec^2 Ø = tan^2 Ø + 1 (1-√3tanθ)+1+√3 = √3sec^2θ 1 - √3tanØ + 1 + √3 = √3(tan^2 Ø + 1) - √3tanØ + √3 = √3tan^2 Ø + √3 tan^2 Ø + tanØ = 0 ...
*February 21, 2016*

**Algebra**

1/x^2-4x-12 = 1/( (x-6)(x+2) ) undefined for x = -2 or x = 6 (we would be dividing by zero)
*February 21, 2016*

**Math Algebra**

I think you are missing something here. "Three time the 1st is .??.. more than twice the second the way it stands: one number --- x the other ----- 50-x 3(x) > 2(50-x) 3x > 100 - 2x 5x > 100 x > 20 So possible solutions: If our domain is the set of whole ...
*February 21, 2016*

**Math Pre-Cal (Exponential Functions)**

assume that 1956 represents a time of t=0 and t is the number of years since 1956 so 1974 ---> t = 8 2016 ---> t = 60 If m is the minimum wage, then m = 1 e^(kt) when t = 8 , m = 2 2 = e^(8k) 8k = ln2 k = ln2/8 so m = e^( (ln2/8)t) when t = 60 m = e^(60(ln2/8)) = 181.02 ...
*February 21, 2016*

**algebra or algebra1**

One of the factors is ?? 3x^2+18x+24 = 3(x^2 + 6x + 8) = 3(x+2)(x+4)
*February 21, 2016*

**algebra or algebra1**

annual interest = .04x + .05(10000-x)
*February 21, 2016*

**algebra or algebra1**

Wow, why are you typing like this ? f (x) =|x− 6|7−x, then f(−1) the |x-6|7 makes little sense. in algebra, a coefficient is usually written in front e.g. 5x instead of x5 did you mean |x-6|^7 ?
*February 21, 2016*

**algebra or algebra1**

the ^ is written in front of the exponent, so I will interpret your typing as: ( x^7 (-y^8 z^5)^2 )^3 = ( x^7(-y^16 z^10)^3 = ( - x^7 y^16 z^10)^3 = - x^21 y^48 z^ 30 the problem is the -y^8 If you meant (-y)^8, then the result would be +
*February 21, 2016*

**Math Pre-Cal (Exponential Functions)**

let 1985 <---> t = 0 then 2005 --> t = 20 2010 -----> t = 25 let the rate of appreciation be i (just like interest rate with money) 110000(1+i)^20 = 145000 (1+i)^20 = 1.3181818.. take 20th root 1+i = 1.013909 i = .0139 or appr 1.39 % (that's lousy) value in ...
*February 21, 2016*

**Math**

write it as f(x) = x^(1/2), and it becomes a routine question f ' (x)= (1/2)x^(-1/2) or -1/(2√x)
*February 20, 2016*

**math**

1. number of 2-topping pizzas = 6x5 or 30 2. Assuming one sauce and 2 topping, number of pizzas = 2x6x5 = 60 3. Assuming the previous as well, now we have 2 x 2 x 6 x 5 = 120
*February 20, 2016*

**Calculus**

disagree, the value of sinx fluctuates between -1 and 1, so as x approaches infinity, adding or subtracting a number between 0 and 1 will be insignificant. The values of f(x) and g(x) will differ by at most 1 - their rates of growth would vary just be a bit My pick would be ...
*February 20, 2016*

**Calculus**

make a sketch. let the length of the man's shadow be x let the distance between the man and the post be y by ratios: 1.7/x = 5/(x+y) 1.7x + 1.7y = 5x 1.7y = 3.3x 17y = 33x 17 dy/dt = 33 dx/dt given: dy/dx = 2.9 33 dx/dt = 17(2.9) dx/dt = 17(2.9)/33 = appr 1.5 m/s notice ...
*February 20, 2016*

**ruby**

don't understand how you came up with that answer. old sandbox : 6 by 10 so perimeter = 32 ft area = 60 ft^2 new sandbox : 12 by 20 new perimeter = 64 --> it doubled, so a 100% increase, the multiplication factor is 2 new area = 240 ft^2 --> it quadrupled so the ...
*February 20, 2016*

**Calculus**

yes, e^(4x) grows at the fastest rate e.g. let x = 20, (not very large at all) 3^20 = 3.48 x 10^9 ln(20) = only about 3 e^(4x) = 5.5 x 10^34 <------ 20^10 = 1.024 x 10^13
*February 20, 2016*

**Calculus**

yes, ex would be linear,
*February 20, 2016*

**algebra**

compare their slopes For Ax + By = C the slope = -A/B ( you can do the calculation in your head) slope of given line = -2/3 slope of first choice = 6/4 = 3/2 , nope etc
*February 20, 2016*

**Algebra**

While you walk .75 miles, your friend will walk (1/2)π(.75) miles , (since C =πd) the extra distance is the difference between them.
*February 20, 2016*

**algebra 2**

since we know the vertex is (3,-20) we can start with y = a(x-3)^2 - 20 plug in the other point (7,12) 12 = a(4)^2 - 20 32 = 16a a=2 y = 2(x-3)^2 - 20
*February 20, 2016*

**Please help me on math, thanks!**

There are 4 digits to fill 2 spaces number = (4)(3) = 12
*February 20, 2016*

**High school calculus**

Two b or not two b
*February 20, 2016*

**@ George - Algebra**

Why did you not respond to my original concern here? http://www.jiskha.com/display.cgi?id=1455973924
*February 20, 2016*

**math**

Your formula is incorrect, should say V = (4/3)π r^3 for your given ... V = (4/3)π(7.3)^3 = ....
*February 20, 2016*

**Math**

A is correct
*February 20, 2016*

**Algebra**

duplicate post, I just did it
*February 20, 2016*

**Algebra joint, inverse and direct variation**

t = k (1/z^3)(r^2) for the given: 4 = k(1/27)(36) k = 4(27)/36 = 3 so your equation is t = 3r^2/z^3 for the data ... t = 3(81)/216 = 9/8 or 1.125 #2 c = k d^2/l sub in the given: .54 = k (9)/20 k = .54(20)/9 = 1.2 so you have c = 1.2 d^2/l in your first data, the length was ...
*February 20, 2016*

**math**

let those terms be a, ar and ar^2 T2 = T1 - 4 --> ar = a - 4 a(r-1)=-4 a = 4/(r-1) T3 = T2 + 9 ar^2 = ar + 9 a(r^2 -r) = 9 a = 9/(r^2-r) -4/(r-1) = 9/(r(r-1)(r+1)) -4 = 9/r r = -9/4 then a = -4/(-9/4 - 1) = 16/13 the terms are: 16/13 , (16/13)(-9/4) , (16/13)(81/16) = 16/13...
*February 20, 2016*

**Maths**

It is hard to decipher your wording but I will try. Let a parallel line from the top of the platform meet the height of the building at C Label the top of the building A, and its bottom as B tan56° = AC/10 --> AC = 10tan56 tan39° = BC/10 --> BC = 10tan39 height ...
*February 20, 2016*

**Math**

Number of ways to take any "three" = C(11,3) = 165 number of ways to select 3 cherries from 6 = C(6,3) = 20 prob (3 cherries) = 20/165 = 4/33 direct way: prob(3 cherries) = (6/11)(5/10)(4/9) = 4/33
*February 20, 2016*

**Maths**

I did this for you. Always check back before posting the same problem again http://www.jiskha.com/display.cgi?id=1455895262
*February 20, 2016*

**precal11**

In terms of acute angles and by the CAST rule cos 135 = -cos45 sin 225 = -sin 45 and since I know that sin45 = cos56 cos135° = sin225°
*February 19, 2016*

**Math**

If 7/10 are adults, then 3/10 are children ratio of adults : children = 7 : 3 = 7x : 3x 7x - 3x = 48 x = 12 3x = 36 7x = 84 10x = 120 there are 120 at the clubhouse, of which 84 are adults and 36 are children
*February 19, 2016*

**calculus**

Question: Does the firefighter clim up 2 ft/sec along the length of the ladder , or 2 ft/sec vertically ?
*February 19, 2016*

**Finance**

amount = 25500( 1 + .09/12)^18 = ...
*February 19, 2016*

**Maths**

for the AP first term = a 2nd term = a+d fifth term = a+4d but these also form a GP, so (a+d)/a = (a+4d)/(a+d) a^2 + 2ad + d^2 = a^2 + 5ad 3ad = d^2 d = 3a common ratio = (a+d)/a = (a+3a)/a = 4
*February 19, 2016*

**Math**

just replace the x with the given values e.g. for the first one, x = 6 y = 2(6) - 4 = 12-4 = 8 now try the other two values of x should be simple.
*February 19, 2016*

**Math (Pre-Cal) (Exponential Functions)**

let the rate of depreciation be r 38000(1-r)^6 = 11000 (1-r)^6 = 11/38 1-r = (11/38)^(1/6) 1-r = .8133326 r = .186667 rate of depreciation is 18.67 % so in 2012 it will be 38000(.8133326)^10 = $4813.55
*February 19, 2016*

**Maths**

On the elevator you would have: the worker + the trolley + the bricks = 73 + 100 + x = 1500 x = 1327 So we can have 1327 kg of bricks each brick weight 330/5 or 66 kbg number of those = 1327/66 = 20.1 so we could take 20 bricks at a time
*February 19, 2016*

**math**

nephew ---- x Kim ------ 3x + 15 3x+15 = 36 3x = 36-15 3x = 21 x = 7 State your conclusion and check if the answer is correct.
*February 19, 2016*

**Math**

A straight line has only 1 dimension, namely length, so we might measure the length of a line segment to be 12 cm (the cm is really cm^1 ) Now take a piece of graph paper. Usually lines are drawn that are at right angles to each other at certain intervals. Suppose they are ...
*February 19, 2016*

**Math**

since any given line segment can have only ONE midpoint, and the perpendicular bisector has to go through the midpoint, there will be only ONE of them B is correct
*February 19, 2016*

**math**

ok, so you have k^2 - k - 3 where does the division come in ?
*February 19, 2016*

**Math- 2 questions!**

correct
*February 19, 2016*

**Algebra**

amount in B -- x amount in A -- 3x .06(3x) + .07x = 2250 .18x + .07x = 2250 .25x = 2250 x = 9000 so $9000 in B and $27,000 in A
*February 18, 2016*

**Finance**

What about the initial $25,000 that he starts with ? i = .06/12 = .005 25000(1.005)^324 + R(1.005^324 - 1)/.005 = 1,000,000 R(806.5468...) = 874,181.64 R = $1083.86
*February 18, 2016*

**Math**

hard to draw trees here, will do it in listing form we want E to win, as soon as they win 2 games it is all over, no more than 3 games Possible ways: EE = .6^2 = .36 ERE = .6(.4)(.6) = .144 REE = .144 prob = sum of those = .648
*February 18, 2016*

**Pre-Calculus**

solve each for t x = 9t+2 9t = x-2 t = (x-2)/9 y = 2t-2 2t = y+2 t = (y+2)/2 so (x-2)/9 = (y+2/2 cross-multiply 2x - 4 = 9y + 18 2x - 9y = 22--> I would have like that from -9y = -2x + 22 y = (2/9)x - 22/9 -- looks like the a)'s have it.
*February 18, 2016*

**Algebra**

width ---- x m length ---- x+30 320 < 2x + 2(x+30) < 360 320 < 4x + 60 < 360 260 < 4x < 300 65 < x < 75
*February 18, 2016*

**algebra**

#2 - ok #3 x/5+6=10 x/5=4 x = 20 #4 -2(m-30) = -6m -2m + 60 = -6m 4m = -60 m = -15 #5 3.75x+3.7=1.7+1.75x 2x = -2 x = -1
*February 18, 2016*

**math**

number of ways to choose 10 from 22 = C(22,10) what can't we have: choosing 5 plays + choosing 6 plays = C(6,5)xC(16,5) + C(6,6)xC(16,4) number of ways = C(22,10) - ( C(6,5)xC(16,5) + C(6,6)xC(16,4) ) = 646646 - (26208+1820) = 618618 or in scientific: 6.19x10^5 (but why ...
*February 18, 2016*

**Math**

multiply each term by 5x, the LCD 10 - x^2 = x -x^2 - x + 10 = 0 x^2 + x - 10 = 0 x = (-1 ± √41)/2 --> exact answer, or = appr 2.702 or -3.702
*February 18, 2016*

**Math**

Surely you can do better than 3.1 for π Calculators have π built-in with about 10 decimal place accuracy. area of mat = 25π m^2 cost per m^2 = 15.5/(25π) dollars/m^2 = .197.. or 20 cents/m^2 You found how many m^2 we can get for $1.00
*February 18, 2016*

**Math**

Peter' age --- x Veronica ---- x+2 x + x+2 = 24 take over
*February 18, 2016*

**northdale middle school**

looks like they are charging $9 per hour so Cost = 9t, where t is in hours
*February 18, 2016*

**math**

first term -- a term3 = a + 2d, but term3 = 4a 4a = a+2d 3a = 2d term6 = a + 5d = 17 or a = 17-5d sub that into 3a = 2d 3(17-5d) = 2d 51 - 15d = 2d 51 = 17d d = 3 then 3a = 6 a = 2 terms are: 2, 5, 8, 11, 14, 17 , all checks out, the fourth terms is 4 times the first and the ...
*February 18, 2016*

**PreCalc**

look back at your earlier post of this question.
*February 18, 2016*

**math**

width --- x length --- x+7 2x + 2(x+7) = 62 solve for x
*February 18, 2016*

**maths-probability**

to get 4: 1,3 2,2 3,1 --- there are 3 cases prob(4) = 3/36 = 1/12
*February 18, 2016*

**Geometry**

agree
*February 18, 2016*