Tuesday

September 2, 2014

September 2, 2014

Total # Posts: 27,020

**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*

**algebra/what am I doing wrong Please help**

You should have definitions for dependent, independent, and incosistent. if there is a unique solution , the system would be independent. since the two lines have different slopes, they MUST intersect in a point, thus independent Wolfram is great ... http://www.wolframalpha....
*June 11, 2014*

**Please help me with this question.!!!!!!**

I must admit that I had no idea what a "box and whisker" plot is, even though I taught math for 35 years, so I looked it up and found this video of the very useful Khan Academy by Sal Khan https://www.khanacademy.org/math/probability/descriptive-statistics/Box-and-...
*June 10, 2014*

**Algebra**

prob on base = .45 prob not on base = .55 prob (on base 5 of 7 times) =C(7,5) (.45^5)(.55^2) = appr .117
*June 10, 2014*

**Math**

-4x-8>4 -4x > 12 divide both sides by -4 x < -3 You add and subtract jus like you would for an equation, but when you divide by a negative, like I did in the last step, you MUST reverse the inequality sign.
*June 10, 2014*

**math (cant figure it out)**

Prob(vowed, then Q) = (3/6)(1/6) = 3/36 = 1/12 How did you possible get 1/10 ?
*June 10, 2014*

**math *check***

Strike 2 prob (red from 1st then red from 2nd) = (12/20)(8/13) = 24/65
*June 10, 2014*

**algebra**

what is 4^3 - 5(4^2) + 4 ?
*June 10, 2014*

**math**

1/8 = .125 or 12.5% so to double we would solve 1(1.125)^n = 2 log both sides log (1.125^n = log2 n log 1.125 = log2 n = log2/log 1.125 = appr 5.885 years for tripling, solve 1.125^n = 3 ------> you should get appr 9.33
*June 10, 2014*

**math *check***

prob(green) = 9/20 prob(not green) = 11/20 odds in favour of green = (9/20) : (11/20) = 9: 11 you are correct.
*June 10, 2014*

**math (cant figure it out)**

Valid point by Writeacher, if they they are numbered from 0-10 , there would be 11 sections. Clarify before I answer it.
*June 10, 2014*

**math**

strange wording .... " Finding three geometrically numbers" I assume you have 3 numbers in a geometric sequence. "30 units exceeds the sum of the other two" ...... which "other two" , the first two, the last two , or the middle two ? the three ...
*June 10, 2014*

**Math**

Use Cartesian geometry let the first be at (1,120) and the last one at (7,12) slope = (120-12)/(1-7) = -18 so for each increase in x, the height drops 18 cm so you want two decreases, height of third = 120-2(18) = 84 or find the equation: y = -18x + b at (7,12) 12 = -18(7) + b...
*June 10, 2014*

**math -interest**

i = .14/12 = .0116666... n = 12 400 = payment (1 - 1.011666...^-12)/.01166.. I get payment = 35.91
*June 10, 2014*

**Algebra 1**

y = x^2 - 4x+ 4 = (x - 2)^2 for x-intercept, let y = 0 (x-2)^2 = 0 x-2 = 0 x = 2 we have a double root at x = 2 , ( x=2 or x=2) see Wolfram: http://www.wolframalpha.com/input/?i=plot+y+%3D+x%5E2+-+4x+%2B+4 Usually , I would put my money on Wolfram.
*June 10, 2014*

**math**

If f(x) will "vanish" when x = 1 and x = -2 (x-1) and (x+2) must be factors assume we have f(x) = a(x+b)(x-1)(x+2) given: f(-1) = 4 ---> 4 = a(-1+b)(-2)(1) -2a(-1+b) = 4 2a - 2ab = 4 a - ab = 2 f(2) = 28 ---> 28 = a(2+b)(1)(4) 4a(2+b) = 28 8a + 4ab = 28 2a + ab...
*June 10, 2014*

**math**

I see about 9 questions that you posted all dealing with the factor and remainder theorems. You have shown no effort on your part or let us know where you difficulties are. They all basically follow these two concepts : if for some f(x) , x-a is a factor, then f(a) = 0 if for ...
*June 10, 2014*

**math**

p(4) = 64k + 48 - 3 = 64k + 45 Q(4) = 128 - 20 + k = k + 108 by the remainder theorem , each of these are the remainders when divided by x-4 But they are equal ... 64k + 45 = k + 108 63k = 63 k = 1
*June 10, 2014*

**math**

x^3-a^2x+x+2 is divisible by x-a so x=a has to give a result of 0 when subbed in a^3 - a^2 (a) + a + 2 = 0 a^3 - a^3 + a + 2 = 0 a = -2
*June 10, 2014*

**maths**

area = (4)(6)sin52° = ....
*June 10, 2014*

**check answer**

good, carry on
*June 9, 2014*

**algebra**

g^-1 = { (5,-4), (2,3), (0,4)} h^-1(x) = (x-9)/2 g^-1 (2) = 3 h^-1 (x) = (x-9)/2 (h*h^1) (-7) .... is there a typo? did you mean (h*h^-1) (-7) ?? if so, then (h*h^-1) (x) = (2x+9)(x-9)/2 = (2x^2 + 9x - 81)/2 (h*h^-1) (-7) = (98 - 63 - 81)/2 = -23
*June 9, 2014*

**Math**

Basic property of triangles: the largest side is opposite the largest angle the smallest side is opposite the smallest angle etc since angle A is 125° , the sum of the other two angles must be 55° that is, "a" must be the largest side, but b > a which ...
*June 9, 2014*

**Precalculus**

Expected pay-out = .04(300) + .03(400) + (.03)(.04)(6000) = 12 + 12 + 7.20 = $31.20 how did you get 31.40 ? to make a $10 profit, they should charge 41.20 per policy
*June 9, 2014*

**Algebra 1--Please, help me!**

1. for the x-intercept let y = 0 ---> x = 2/3 for the y-intercept , let x = 0 ---> y = -2 2. (3m^2 n)/(5m)(20mn/n^6) = (3mn/5)(20m/n^5) = 12m^2/n^4 ------> a) 3. 3/x + 3/(5x) LCD = 5x = 15/(5x( + 3/(5x) = 18/(5x)-----> c)
*June 9, 2014*

**Algebra**

domain: { -7,9,0} range : { 5,-4,3,-7}
*June 9, 2014*

**Algebra 1--Please, check my answer!**

1. the slope of x+2y = -6 is -1/2 so we are looking for a line with slope +2 so anything starting with 2x-y = .... or -2x + y = ... will do. looks like b) to me 2. They all factor and simplify a) 3(x+2)/((x+2)(x-1)) = 3/(x-1) , x ≠ -2 b) 3(x-1)/((x-1)(x-1)) = 3/(x-1) , x...
*June 9, 2014*

**algebra/can you show me how to solve problem**

f(x) = x^2 + 2 f(-3) = (-3)^2 + 2 = 9+2 = 11 notice that I substituted x with the given value of x wherever I saw an x do the others the same way
*June 9, 2014*

**Algebra 1--Please, help me!**

see later post
*June 9, 2014*

**Algebracan you answer my question**

http://www.wolframalpha.com/input/?i=plot+x-y%3D4+%2C+2x%2B3y%3D13+
*June 9, 2014*

**Math**

let y = -x^2 + 5x + 5 dy/dx = -2x + 5 = 0 for a max of y 2x = 5 x = 5/2 when x = 5/2 y = -25/4 + 5(5/2) + 5 = 45/4 you should recognize y = -x^2 + 5x + 5 as a downward opening parabola , the max is 45/4 when x = 5/2
*June 9, 2014*

**Calculus**

if f ' (x) = 2x- 3x^2 f(x) = x^2 - x^3 + c f(0) = 0-0+c f(3) = 9 + 27 + c = 36+c change from f(0) to f(3) = 36+c - c = 36
*June 9, 2014*

**algebra**

Your expansion is incorrect 3(x-5)(x+5) = 3(x^2 - 25) = 3x^2 - 75 Since you wanted a quadratic equation, it should be 3x^2 - 75 = 0
*June 9, 2014*

**algebra**

What did you get ?
*June 9, 2014*

**Algebra**

follow the same steps that I showed you in your previous post of the identical type of question. It appears you never even looked at it.
*June 9, 2014*

**Algebra**

that would simply be f(x) = 2(x+3)(x+4) = 2x^2 + 14x + 24
*June 9, 2014*

**Math**

1by1 --- 64 of them 2by2 --- 49 3by3 --- 36 4by4 --- 25 5by5 --- 16 6by ----- 9 7by7 ---- 4 8by8 ---- 1 total = 204 There can only be an equal number of reds and blacks in the even-numbered squares, so 64 + 36 + 16 + 4 + 1 = 121 121 blocks have the same number of reds and ...
*June 9, 2014*

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