Thursday

December 18, 2014

December 18, 2014

Total # Posts: 28,251

**maths**

let the roots of the first be s and 4r let the roots of the second be s and 3r 1st: x^2 - 6x + a = 0 sum of roots = 6 product of roots = a s+4r = 6 and 4rs = a 2nd: x^2 - cx + 6 = 0 sum of roots = c product of roots = 6 s+3r =c and 3rs = 6 ---> rs = 2 so in 4rs = a , we ...
*July 5, 2014*

**maths**

Sachins would have been (x-4)(x-3) = 0 x^2 - 7x + 12 = 0 Rahul's would have been (x-3)(x-2) = 0 x^2 - 5x + 6 = 0 Sachin was wrong with the 12, should have been 6 Rahul was wrong with the -5x , should have been -7x Equation should have been x^2 - 7x + 6 = 0 (x-6)(x-1) = 0 x...
*July 5, 2014*

**algebra**

amount of the 30% solution needed ---- x L amount of the 16% solution needed --- 5-x L .3x + .16(5-x) = .272(5) times 100 30x + 16(5-x) = 136 30x +80 - 16x = 136 14x = 56 x = 4 L 4 L of the 30%, and 1 L of the 16% solution would be needed.
*July 5, 2014*

**math**

For any linear equation in the form Ax + By + C = 0 , the slope is -A/B So for both of your equations, the slope is -1/3 thus they are parallel
*July 5, 2014*

**Algebra**

For a complicated equation such as yours, the most powerful method is probably Newton's Method. let y = 3x^2+4lnx+4 dy/dx = 6x + 4/x newx = x - y/(dy/dx) = x - (3x^2+4lnx+4)/(6x + 4/x) which simplifies to newx = (3x^2 - 4lnx)/(6x + 4/x) now use an iteration process, I ...
*July 3, 2014*

**algebra**

Vikky, what Steve is telling you that complex roots, as well as irrational roots, always come in conjugate pairs. e.g. if one root is 5 - 7i, then there has to be a matching 5 + 7i e.g. if one root is (4 + 3√5)/2 , then there has to be a (4 - 3√5)/2 So, if you know...
*July 2, 2014*

**math**

Using a ruler and compass, draw the base line of 9 inches. Set your compass to 6 inches, from the left end of the base draw an arc above the base line. Set your compass to 4 inches, from the right end of the base, draw an arc above the base line The intersection of the two ...
*July 2, 2014*

**Math**

To be an arithmetic progression, (2t-1) - t = (2t+4) - (2t-1) solve for t
*July 2, 2014*

**math**

what is 60 + (2/5)(60) ?
*July 2, 2014*

**algebra math**

I don't see any obvious relationship, nor does Wolfram http://www.wolframalpha.com/input/?i=plot+%7B%282%2C3%29%284%2C5%29%286%2C4%29%288%2C6%29%2810%2C5%29%2812%2C12%29%2814%2C16%29%2816%2C22%29%2818%2C26%29%2820%2C32%29%7D
*July 2, 2014*

**mat/simultaneous equation**

I would use elimination here 1st times 3 ---> 6x - 15y = 39 2nd times 5 --> 25x - 15y = -75 subtract them: -19x = 114 x = -6 back into 1st -12 - 5y = 13 -5y = 25 y = -5 x = -6 , y = -5
*June 29, 2014*

**calculus**

Assuming we take the growth to be exponential , ... 5 e^(28r) = 7.5 e^(28r) = 1.5 ln both sides ln (e^(28r)) = ln1.5 28r = ln 1.5 r = .0145 the rate is 1.45% check: 5 e^(28*.0145) = 7.5
*June 27, 2014*

**maths probability**

Answered by MathMate a few days ago under a Physics heading http://www.jiskha.com/display.cgi?id=1403632512
*June 27, 2014*

**math**

In a 32:3 ratio, there are 35 parts 7 m or 700 cm divided by 35 = 20 cm by part So what do you think?
*June 27, 2014*

**Math**

I get 3t-9-20t+15 = 5-42t-7 25t = -8 t = -8/25
*June 26, 2014*

**Math**

I will assume you mean 120a^4b^2/(-24a^9b^-15) if so, then it would be -5 a^-13 b^17 or -5b^17/a^13
*June 26, 2014*

**Algebra 1**

Use this notation to indicate exponents: x^3 - x^2 - 4x + 4 = 0 grouping will work x^2(x - 1) - 4(x - 1) = 0 (x-1)(x^2 - 4) = 0 (x-1)(x+2)(x-2) = 0 so x = 1 , -2 , +2
*June 26, 2014*

**Algebra**

yes
*June 26, 2014*

**calcus**

Isn't that just a straight-forward Pythagorean calculation? Surely somebody who studies Calculus MUST know how to do that. Let me know where your problem lies.
*June 26, 2014*

**maths**

Again, having a hard time trying to establish the order of operation. e.g. #3 I put it into Wolfram the way you typed it , and the webpage interpreted it the same way I did http://www.wolframalpha.com/input/?i=+X%5Elogx%2B5%2F3%3D+10%5E5%2Blog+x What a messy equation that ...
*June 26, 2014*

**maths**

1. by definition of logs x^2 - 12x + 36 = 10^2 (x-6)^2 = 100 x-6 = ±√100 = ±10 x = 6 ± 10 = 16 or -4 2. you have the product of 3 numbers = 0 so one of them is zero but log4 and log2 are non-zero real numbers, so log2x must be 0 that is, x = 1 3.not ...
*June 26, 2014*

**maths**

11^(1/2) = √11 since 11 is not a perfect square, 11^(1/2) is irrational
*June 26, 2014*

**maths**

1st number --- x 2nd number -- 8-x sum of squares = x^2 + (8-x)^2 = x^2 + 64 - 16x + x^2 = 2x^2 - 16x + 64 d(sum of squares)/dx = 4x - 16 = 0 for max/min 4x=16 x = 4 the two numbers are both 4 check: for the answer, sum of squares = 16+16 = 32 let 1st be 3.99, the other 4.01 ...
*June 26, 2014*

**math**

first you need the monthly payment. i = .11/12= .00916666.. n = 12 Paym (1 - 1.0091666..^-12)/.009166.. = 15000 paym = 1325.72 Here are my titles to the amortization table ( they will not line up niceley) Time - payment - interest - repayment - balance now -- 0.00 -- 0.00 -- 0...
*June 26, 2014*

**math**

prob = C(4,3)*C(4,3)/C(52,6) = 16/20,358,520 4/5089630
*June 25, 2014*

**math-Ms Sue please help**

I am pretty sure that for loans lasting 25 years, compound interest would be used. i = .10/12 = .008333... n = 25(12) = 300 payment( 1 - 1.008333^-300)/.0083333) = 73700 I get payment = $ 669.71
*June 24, 2014*

**math**

All your questions deal with the use of our 4 basic compound interest formulas. What exactly do you not understand about these questions ? They all are very straight forward.
*June 24, 2014*

**math**

i = .08/12 = .006666.. n = 18(12) = 216 amount = 225( 1.00666..^216 - 1)/.00666.. = ... you do the button pushing
*June 24, 2014*

**math**

amount(1.02)^12 = 15000 amount = 11827.40
*June 24, 2014*

**math**

amount after 3 years at 5% pa compounded semiannually = 4494(1.025)^6 = 5211.66 so interest = 5211.66-4494 = 717.66
*June 24, 2014*

**math**

how about y = x^3/(x-1) confirmed: http://www.wolframalpha.com/input/?i=plot+y+%3D+x%5E3%2F%28x-1%29
*June 23, 2014*

**algebra**

√50 = √25√2 = 5√2, which is choice A
*June 23, 2014*

**MAT 221**

-10 < -2 + 8x < 22 add 2 -8 < 8x < 24 divide by +8 , (no change in inequality sign) -1 < x < 3 Can't make out your symbols in the 2nd e.g. use <= for ≤ and >= for ≥
*June 23, 2014*

**Frequency**

assuming that they either supported it or not supported it, P(E) = 80/400 = 1/5
*June 22, 2014*

**Algebra**

yes, I would put your answer in set form, using { } brackets, eg. range = {2,-5}
*June 21, 2014*

**Trigonometry help**

Depends on the interpretation of "makes a 15° angle with the boat". If the rope makes a 15° angle with the water line, (parallel to the bottom of the boat) you would have: depth/24 = cos 75° or depth/24 = sin 15° , both giving you depth = 6.21 If the ...
*June 21, 2014*

**Math**

1 term(n) = ar^(n-1) term(10) = 16(-1/2)^9 = 16(-1/512) = - 1/32 2. ar^9 = 3/512 ar^14 = 3/16384 divide the 2nd by the first r^5 = 1/32 r = 1/2 back into the first a(1/2)^9 = 3/512 a(1/512) = 3/512 a = 3(512)/512 = 3
*June 18, 2014*

**Math**

looks like an arithmetic sequence with d = 17 and term2 = -243 a+d = -243 a = - 260 term(67) = a+66d = -260 + 66(17) = ... you should have at your finger-tips the formulas for the sum of n terms you have the a and the d, so plug in
*June 18, 2014*

**oops - finite math**

that should be .25 + .47 for OR the way I had it would have been for AND
*June 17, 2014*

**finite math**

what is .25(.47) ?
*June 17, 2014*

**finite math**

How many of the 59 homeruns went to left field ?
*June 17, 2014*

**geometry**

Did you carefully read the question ?
*June 17, 2014*

**geometry**

let me rephrase the question ... what is the greatest common factor of 720, 1008, and 672 ? 720 = 8*9*10 = 16*3*3*5 1008 = 8*9*14 = 16*3*3*7 672 = 16*3*2*7 so who is common? looks like 16*3 or 48 check: 720/48 = 15 1008/48 = 21 672/48 = 14 , nothing common in any of those 3 ...
*June 17, 2014*

**Math**

well, let's put z=2 into the 2nd z=y + 2 = 5 y = 3 So now we know that z=2 and y = 3 now into the 1st: x - 6 + 2 = 8 z = 12 So, where was your problem with this ? Looks very very easy.
*June 17, 2014*

**Math**

use term(n) = a + (n-1)d here a = -847 , d = 11 , n = ?? , and term(n) = -11 solve : -11 = -847 + (n-1)(11) which should be pretty straightforward to do.
*June 17, 2014*

**probability and statistics**

Ummmh, if everybody got an 85, wouldn't the average be 85 ??? , so mean = 85 and since nobody "deviated" from that score, wouldn't the standard deviation be zero ????
*June 17, 2014*

**Math**

It must be true that (2x-1) - (3x-2) = (4x-3) - (2x-1) -x + 1 = 2x - 2 -3x = -3 x = 1 check: terms would be 1 , 1, 1 strange sequence but it is arithmetic
*June 17, 2014*

**Math**

so you are adding 64 + 81 + 98 + ... for 17 terms a = 64 d = 17 n = 17 use the formula Sum(17) = (17/2)[128 + 16(17)] = 3400
*June 17, 2014*

**algebra**

so -2x^2 + 8x + 5 = 0 x^2 - 4x = 5/2 complete the square ... x^2 - 4x + 4 = 5/2 + 4 (x-2)^2 = 13/2 = 26/4 x-2 = √26/4 ........ since √26 is close to 5 x = appr 2 ± 5/2 = appr 4.5 or .5
*June 17, 2014*

**Math**

I saw this question and have not been able to get a handle on it we know that ln(x) has an expansion formula http://upload.wikimedia.org/math/6/d/b/6dbf56b2e5f34d298c1e71ddd93b3448.png but it only good for |x-1| < 1 so we could create a series of terms = 1/(x+1) ( (x-1) - (...
*June 17, 2014*

**geometry**

let the mean be x (1/8) / x = x / (8/32) x^2 = (1/8)(8/32) x^2 = 1/32 x = ± 1/√32 or ± 1/(4√2) or ± √2/8
*June 17, 2014*

**Math**

a=2 ,d=4 term(12) = a+11d = 2 + 44 = 46
*June 17, 2014*

**Math**

a = x-y d = 2x+y-3 just use your formula term(101) = a + 100d = x-y + 100(2x+y-3) = x-y + 200x + 100y - 300 = 201x + 99y - 300
*June 17, 2014*

**Maths**

You will need brackets to properly identify the order of operations. you probably mean : 5/(1/2) + 14( 5/(1/2) + 14)(1/4) which is 10 + 14(10+14)/4 = 10 + 60 = 70 As to the relationship between the two number ??? yes, you are right, they are both whole numbers or they are both...
*June 17, 2014*

**Math**

surface area = 2π(2.5)^2 + 2π(2.5)(9) = ---
*June 17, 2014*

**MATH**

Your solution is illustrated by http://www.google.com/search?q=intersection+of+3+planes&tbm=isch&imgil=VKeuvId73BKgcM%253A%253Bhttp%253A%252F%252Ft2.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcTP5OK2B8xVEFseHgCh5S25ao2K4pX-fClEpupY9ltfPRK6cZC8NA%253B332%253B265%...
*June 17, 2014*

**MATH**

if you divide the 2nd by 2, all your equations start with 2x. That is good, since we could add or subtract them to eliminate the x 2x+y-3z=4 2x+z=10 -2x+3y-13z=-8 subtract 1st from the 2nd -y + 4z = 6 , #4 add the 2nd and 3rd 3y - 12z = 2 , #5 #4 times 3---> -3y + 12z = 18...
*June 17, 2014*

**algebra**

Did you mean, are the lines through each pair of points parallel or perpendicular to each other ?
*June 17, 2014*

**Angles,Lines and Triangles**

let the angles be x and y x+y = 116 x-y = 24 add them 2x = 140 x = 70 then y = 46 one angle is 70°, the other is 46° leaving 64° for the third angle
*June 17, 2014*

**math**

use a simple ratio ... miles/7 = 64/80 miles = 7(64/80) = 5.6
*June 17, 2014*

**Math**

since it is parallel to y=x/2 + 4 it will differ only in the y-intercept, so let y=x/2 + b plug in the point(10,12) 12 = 5+b b = 7 y = x/2 + 7
*June 16, 2014*

**algebra 2**

Since you labeled it algebra rather than Calculus, I will use an algebraic solution, completing the square h(t) = -16(t^2 - 9t + 81/4 - 81/4) + 24 = -16( (t - 9/2)^2 - 81/4) + 24 = -16(t - 9/2)^2 + 324 + 24 = -16(t-9/2)^2 + 348 this is a downwards-opening parabola with vertex...
*June 16, 2014*

**Math**

#1 and #2 are the same type as the ones I just did for you Give them a try #3 a=2 , d=4 a+(n-1)d = term(n) 2 + (n-1)(4) = 106 2 + 4n - 4 = 106 4n = 108 n = 27 term(27) = 106
*June 15, 2014*

**Math**

common difference = 4+p - (6-p) = 4+p - 6 + p = 2p - 2 term(101) = a+100d = 6-p + 100(2p-2) = 6-p + 200p - 200 = 199p - 194
*June 15, 2014*

**Math**

a+32d = -2p a+ 60d = 26p subtract: 28d = 28p d = p a + 32p = -2p a = -34p
*June 15, 2014*

**Maths**

R(t) = e^kt, where R(t) is the percentage remaining after t t years, k is a constant given: when t = 50 , R(50) = .6 .6 = e^(50k) ln both sides ln.6 = 50k lne k = ln.6/50 R(t) = e^( (ln.6/50) t)
*June 15, 2014*

**Math**

volume = h(50-2h)^2
*June 15, 2014*

**add maths**

OP /PA = 1/3 3OP = AP now follow the same method I just showed you in your previous post
*June 14, 2014*

**add maths**

let the point be P(x,y) then PA = 2PB √( (x-1)^2 + y^2) = 2√( (x+2)^2 + y^2) square both sides and expand x^2 - 2x + 1 + y^2 = 4(x^2 + 4x + 4 + y^2) x^2 - 2x + 1 + y^2 = 4x^2 + 16x + 16 + 4y^2 3x^2 + 18x + 3y^2 = -15 x^2 + 6x + y^2 = -5 complete the square: x^2 + ...
*June 14, 2014*

**Word Problem**

let the length and width be 4x and 3x old area = (4x)(3x) = 12x^2 new length = 4x+4 new width = 3x + 2 new area = (4x+4)(3x+2) = 12x^2 + 20x + 8 12x^2 + 20x + 8 = 2(12x^2) = 24x^2 12x^2 - 20x - 8 = 0 3x^2 - 5x - 2 = 0 (x-2)(3x + 1) = 0 x = 2 or x = -1/3, which is not ...
*June 13, 2014*

**lehman**

number of $30 units ---- x number of $20 units ---- 2x number of $10 units ---- 40000-x-2x = 40000-3x 30x + 20(2x) + 10(40000-3x) = 800000 30x + 40x + 400000 - 30x = 800000 40x = 400000 x = 10,000 so 10,000 of the $30 units 20,000 of the $20 units 10,000 of the $10
*June 13, 2014*

**lehman**

amount invested at 10% --- x amount invested at 8% ---- 3x amount invested at 9% ----- 700,000-x-3x = 700,000-4x .1x + .08(3x) + .09(700000-4x) = 60500 times 100 10x + 8(3x) + 9(700000-4x) = 6050000 34x + 6300000 - 36x = 6050000 -2x = -250,000 x = 125,000 amount borrowed at 10...
*June 13, 2014*

**math**

Here is the "magic" square, where not only are your diagonals equal to a sum of 15, but so are each row and column 8 1 6 3 5 7 4 9 2
*June 13, 2014*

**UGRENT HELP, math**

They used the < sign should have used the ≤ for the ones that are equal
*June 13, 2014*

**UGRENT HELP, math**

number = 80(3)^(8/2) = 6480 C is obviously the biggest, followed by A B and D are the same none of the answers match, after you find the typo, I will let you figure it out
*June 13, 2014*

**finance**

first let the 50,000 and the 100,000 ride for the 12 years. Amount = 50000(1.05)^12 + 100000(1.10)^12 = 403,635.65 PLus our annuity of 30,000 for 12 years at 10% = 30000(1.1^12 - 1)/.1 =641,528.51 for a total of $1,045,164.17 Last part: let the rate be i 1,045,164.17 = 102,000...
*June 13, 2014*

**maths**

All four sides are equal, so each side of the rhombus is 8 cm get angle Ø , opposite the 10 cm diagonal 10^2 = 8^2 + 8^2 - 2(8)(8)cosØ cosØ = 7/32, then sinØ = 5√39/32 area = 8(8)sinØ = ... you take over
*June 13, 2014*

**MAth**

4+√(4+x^2) = x √(4+x^2) = x-4 square both sides 4+x^2 = x^2 - 8x + 16 8x = 12 x = 12/8 = 3/2 since we squared the equation, we MUST verify the answer LS = 4 + √(4 + 9/4) = 4 + √(25/4) = 4 + 5/2 = 13/2 RS = 2/3 LS ≠ RS so actually there is no ...
*June 12, 2014*

**Math**

prob(blue, then red) = (10/24)(1/23) = 5/276
*June 12, 2014*

**College Algebra**

from vertex, y = a(x+9)^2 + 8 but (9,4) lies on it, so 4 = a(18^2) + 8 324a = -4 a = -4/324 = -1/81 etc you messed up here: 4=a(18)^2+8 4=a(332) , you added 8 to 324a , you can't add unlike terms
*June 12, 2014*

**College Algebra**

from the given vertex, the equation must be y = a(x+2)^2 + 4 but (0,2) lies on it, so 2 = a(0+2)^2 + 4 2 = 4a + 4 4a=-2 a = -1/2 y = (-1/2)(x+2)^2 + 4
*June 12, 2014*

**Math please help**

let y = 3/x + 4(1-x) = 3/x + 4(1-x)^-1 dy/dx = -3/x^2 -4(1-x)^-2 (-1) = -3/x^2 + 4/(1-x)^2 = 0 for a max/min of y 4/(1-x)^2 = 3/x^2 4x^2 = 3(1-x)^2 2x = ± √3(1-x) 2x = √3 - √3x 2x + √3x = √3 x = √3/(2 + √3) = appr .4641 or 2x...
*June 12, 2014*

**algebra**

D : B = 27 : 16 = D : 64 D/64 = 27/16 D = 64(27/16) = 108
*June 12, 2014*

**Math**

$1 = 82.8/12 francs so he has 12 + 25 or $37 $37 = 37(82.8/12) francs = appr 255.3 francs Time to update that ancient texbook your school is using. France has been using the Euro since 1999
*June 12, 2014*

**Math**

2nd angle --- x 1st angle ---- 4x 3rd angle ---- x+84 x + 4x + x+84 = 180 6x=96 x = 16 1st angle = 4x = 4(16) = 64°
*June 12, 2014*

**ALgebra**

adults --- x children -- 3x solve: 975x + 525(3x) = 30600
*June 12, 2014*

**math**

In terms of cosx cos 3x = 4 cos^3 x - 3cosx , and cos 2x = 2 cos^2 x - 1 so cos 3x = cos 2x 4 cos^3 x - 3cosx - 2cos^2 x + 1 = 0 let cosx = y so we need 4y^3 - 2y^2 - 3y + 1 = 0 I tried y = 1 and sure enough that was a solution. then by synthetic division ... 4y^3 - 2y^2 - 3y...
*June 12, 2014*

**math**

i = .08 n = 40 years a) amount = 3000 ( 1.08^40 - 1)/.08 = appr $777,170.00 b) change the exponent from 40 to 30
*June 12, 2014*

**geometry**

second angle --- x first angle ------ 4x third angle ----- x+84 x + 4x + x+84 = 180 you finish it
*June 11, 2014*

**Math**

dimes--- x quarters -- x+2 nickels --- 3(x+2) = 3x + 6 10x + 25(x+2) + 5(3x+6) = 180 10x + 25x + 50 + 15x + 30 = 180 50x =100 x = 2 so 2 dimes and 4 quarters and 12 nickels check: 10(2) + 4(25) + 5(12) = 180 all is good
*June 11, 2014*

**Introductory Algebra**

Ummmh, isn't it about your school updated those old textbooks? France hasn't used the franc for years, they use the Euro.
*June 11, 2014*

**algebra**

cost of pound of copper ---- x cost of pound of tin -------- x+2 3(x + 2) + 7x = 10(3.85) 3x + 6 + 7x = 38.5 10x = 32.5 x = 3.25 copper sells for $3.25 per pound, and tin sells for $5.25 per pound
*June 11, 2014*

**Math**

I would write it as y = (8x^3)(3x-2)^(-1/2) and use the product rule dy/dx = (8x^3)(-1/2)(3x-2)^(-3/2) (3) + 24x^2 (3x-2)^(1/2) I will let you clean it up a bit
*June 11, 2014*

**Math**

yes, f(-6) = -18-5 = -23 f(4) = 12 - 5 = ........ f(8) = ........ range = { -23, ..... , .... }
*June 11, 2014*

**trig**

3secØ = 5 secØ = 5/3 then cosØ = 3/5 , since secA = 1/cosA Ø = arccos 3/5 = appr53.13° but you wanted the obtuse angle, so Ø = 360-53.13 = 306.87° , because the cosine is positive in quadrant I and IV to the nearest degree it would be...
*June 11, 2014*

**Algebra**

to get the y-intercept, let x = 0, that would leave you with y = 3 for the x-intercept, let y = 0 , that would leave you with x = 3 if the equation is of the form Ax + By = C do the same thing, usually you can do it your head e.g. 5x + 3y = 20 x-intercept is 4 y-intercept is 20/3
*June 11, 2014*

**Algebra**

of course
*June 11, 2014*

**Algebra**

treat it like two ordered pairs (1,295) and (2,272) slope = (272 - 295)/(2-1) = - 23 so equation in the form y = mx + b would be count = -23x + b , were x is the day number so using (1,295) 295 = -23(1) + b b = 318 count = -23x + 318 so on day 3 , x =3 count = -23(3) + 318 = ...
*June 11, 2014*

**data management**

a) z-score for 6 days = (6-7)/2 = -1/2 = -.5 b) go to your table at z = -.5 and find the corresponding probability , multiply by 8000 ( I got 2468 c) repeat the above for 4 days I found this website a great replacement for tables http://davidmlane.com/hyperstat/z_table.html
*June 11, 2014*

**math (please check answer)**

prob = (6/20)(2/19) = 3/95 you were right
*June 11, 2014*

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