Thursday

September 18, 2014

September 18, 2014

Total # Posts: 27,127

**Math**

Pablo --- x yrs old Chita ---- x- 15/4 4(x -15/4) = 43 4x- 15= 43 4x = 58 x = 14 1/2 years old
*February 26, 2014*

**algebra**

The corresponding sides of a regular polygon are in the same ratio, so 8/2 = 29/x 8x = 58 x = 58/8 = 29/4
*February 26, 2014*

**Algebra**

You should be familiar with the vertex form of a parabola as y = a(x-p)^2 + q , where (p,q) is the vertex, so we have: y = a(x-4)^2 - 4 using any of the other given points will give us the a let's use the easiest, (2,0) 0 = a(2-4)^2 - 4 0 = 4a - 4 a= 1 y = (x-4)^2 - 4 is ...
*February 26, 2014*

**Ethiopia(AAU)**

A) f(x) = x^2 e^x , notice how I indicated exponents? f ' (x) = x^2 e^x + 2x e^x = e^x(x^2 + 2x) f'' (x) = x^2 e^x + 2x e^x + 2x e^x + 2 e^x = e^x (x^2+ 4x + 2) here is a graph of your first function http://www.wolframalpha.com/input/?i=y+%3D+x%5E2+e%5Ex type in ...
*February 26, 2014*

**math**

number of men ---- x number of boys ---- 20-x solve for x 60x + 35(20-x) = 900 You should get 8 men .... etc
*February 26, 2014*

**Math**

That was a coincidence and only happens when r = 4 When r = 2, the area and the circumference just happen to be equal, again a coincidence.
*February 26, 2014*

**math**

I like that equation. What about it ?
*February 26, 2014*

**Algebra**

5x^2 - 526 = -651 5x^2 = -125 x^2 = -25 Unless you have another typo, there is no real number solution, since we cannot take the square root of a negative. If you equation was supposed to be 5x^2 - 526x= -651 5x^2 - 526x + 651 = 0 x = (526 ± √263656)/10 = appr 103...
*February 26, 2014*

**Math**

If my middle term is even and it starts with x^2, I always complete the square. x^2 + 14x + 49 = -4 + 49 (x+7)^2 = 40 x+7 = ± √40 = ± 2√10 x = -7 ± 2√10
*February 25, 2014*

**Math**

Use the formula exact values: x = (5 ± √13)/2 Use your calculator to find appr. values
*February 25, 2014*

**Finance**

PV = 235 (1 - 1.006458333..^-48)/.006458333 = $ 9672.48
*February 25, 2014*

**Maths**

A - B = 51 ---> A = B+51 A - C = 108 subtract them -C + B = 57 B = C + 57 C = (15/100)(A+B+C) C = (3A + 3B + 3C)/20 20C = 3A + 3B + 3C 17C = 3A+ 3B 17C = 3(B+51) + 3(C+57) 17C = 3B + 153 + 3C + 171 17C = 3(C+57) + 153 + 3C + 171 17C = 3C + 171 + 153 + 3C + 171 11C = 495 C...
*February 25, 2014*

**Geometry A**

The line y+4 = 3(x+6) does expand and simplify it if you have to
*February 25, 2014*

**algebra**

8| x+3/4|< 2 | x+3/4| < 1/4 x+3/4 < 1/4 AND -x-3/4 < 1/4 x < -1/2 AND -x < 1 x < -1/2 AND x > -1 which matches: -1 < x < -1/2
*February 25, 2014*

**algebra**

2|3 x-5|-8=8 2|3 x-5| = 16 |3 x-5| = 8 3x-5 = 8 or -3x+5 = 8 3x = 13 or -3x = 3 x = 13/3 OR x = -1 choose your matching answer, it is there.
*February 25, 2014*

**Math**

welcome
*February 25, 2014*

**Math**

distance = √( (5-1)^2 + (-4+2)^2 ) = √(16 + 4) = √20 = appr 4.47 I would leave it in exact form of √20 or 2√5
*February 25, 2014*

**algebra**

2(8x-4)-2 x<14x+12 16x - 8 - 2x < 14x + 12 -8 < 12 which is a true statement, thus your inequation is true for all values of x so always
*February 25, 2014*

**algebra**

solve it to see which choice is correct
*February 25, 2014*

**algebra**

2(8 x-4)-<14 x+12 16 x - 8 ≤ 14x + 12 2x ≤ 20 x ≤ 10 what do you think?
*February 25, 2014*

**algebra 1**

let the number of 4-people cars be x then the number of 6-person cars is 15-x 4x + 6(15-x) = 72 4x + 90 - 6x = 72 -2x = -18 x = 9 9 of the 4-person cars and 6 of the 6-person cars
*February 25, 2014*

**Math**

These non-metric units always confuse me, so since I use metric most of the time, I will convert to decimals consider 1 board + 1 gap to be one unit so we have 6.5 + .1875 = 6.6875 inches 6.5 = .25 = 6.75 6.5 + .375 = 6.875 now... 18 feet = 216 216/6.6875 = 2.6932.299.. 216/6....
*February 25, 2014*

**Math**

arggh, just a lot of arithmetic..... time per day open for rides: 6.5 hours = 390 minutes time available per year = 390(365) = 142350 minutes time needed to complete one ride = 3 + 4 + 3 = 10 minutes. (so they can complete 39 rides per day) number of rides per year = 142350/10...
*February 25, 2014*

**Math**

look at the pattern 1 line --- 0 intersection 2 ines --- 1 intersection 3 lines ---- 3 intersections 4 lines ---- 6 intersections 5 lines --- 10 intersections 6 lines ---- 15 intersections ..... the numbers of the sequence 1 3 6 10 15 .... are called the "triangular ...
*February 25, 2014*

**maths**

2nd term = a+d 6th term = a + 5d "the 6th term is 3 times the second term" --> a+5d = 3(a+d) a+5d = 3a + 3d 2d = 2a a = d "the 5th term is 15" ---> a+4d = 15 but a = d 5d = 15 d = 3 then a = 3 "the 4th term is 4 times the first term" --> ...
*February 25, 2014*

**Algebra**

or 100x/(x+314) = 42 cross-multiply ... 100x = 42x = 13188 58x = 13188 x = 13188/58 = 6594/29 or appr 227.38 I took your * to mean multiplication, the common symbol for multiplication If, somehow, you meant it to be an exponent, that is [x/(x+314)]^100 = 42 then take the 100th...
*February 25, 2014*

**German Help Please....**

#1 , ok #2, should be Sie haben den Film lieber. You need the plural, your choice would say "She prefers the film" , which would be singular #3 choice D, yours sounds like a Google translation #4 ok #5 A, B, and C are definitely out, C sounds very clumsy, I would say...
*February 25, 2014*

**Math**

cost = 50 + 2n, where n is the number of pages if n = 75 Cost = 50 + 2(75) = ....
*February 24, 2014*

**Calculus**

Just about every Calculus book I have ever seen uses this question as an introductory example of "rate of change" problem. At a time of t seconds, let the foot of the ladder be x ft from the wall, and the top of the ladder by y ft above the ground> then, x^2 + y^2...
*February 24, 2014*

**math**

sorry about the typo, but I am sure you were able to make sense out of it.
*February 24, 2014*

**math**

I am assumungthere are 26 lower case, 26 upper case and 10 digits that can fill any position number of all possible cases = 62^6 = 5.68 x 10^10 (huge) number without any digits = 52^6 = 1.977 x 10^10 (still huge) so the number of possible cases with at least 1 digit = number ...
*February 24, 2014*

**math**

lower end speed: so far --- time = 70/50 = 1.4 hrs total trip -- time = 154/50 = 3.08 hrs top end speed: so far --- time = 70/57 = 1.23 hrs total trip -- time = 154/57 = 2.701 hrs I don't see a " which of the following" part , so use my results above to match ...
*February 24, 2014*

**math**

to go from 1: 15 to 1:16 the minute hand has moved (1/60)(360)° or 6° but the hour hand has also moved (1/60)(1/60)(360)° or 1/10 ° so the change in angle is 6 - 1/10 ° or 59/10 ° or 5.9°
*February 24, 2014*

**algebra**

On my screen the - was on one line and the 2(.... on the next, so I read it as shown if your statement was -2(2x+9) > -4x + 9 your x's would drop out and you have the situation when you posted as "Lucky". Draw your conclusion.
*February 23, 2014*

**algebra**

4x + 18 > -4x + 9 8x > -9 x > -9/8 which of your answers matches this ?
*February 23, 2014*

**algebra**

26+6b > 2(3b+4) 26 + 6b > 6b + 8 26 > 8 , which is true so it is true for all real values of b
*February 23, 2014*

**math**

Did you notice one parabola opens up, the other one down To have only one point of intersection, they must have a common tangent, that is the slope of one equals the slope of the other for the 1st: dy/dx = 2x+6 for the 2nd dy/dx = -2x - 6 2x + 16 = -2x -6 4x = 12 x = 3 when x...
*February 23, 2014*

**algebra**

What is 5(-6) + 5(-5) ?
*February 23, 2014*

**math**

mmmh, they gave you the equation y = kx^2 when y = 50, x = 10 , so.... 50 = k(100) k = 1/2 your equation is y = (1/2)x^2 now just plug in x = 30 in your head you can do y = 900/2 or 450
*February 23, 2014*

**math**

complete the square to find the centre x^2 -10x + 25 + y^2 = k + 25 (x-5)^2 + y^2= k+25 so the centre must be (5,0), which lies on the x-axis to be tangent to the y-axis it must pass through (0.0) and its radius must be 5 so the equation must be (x-5)^2 + y^2 = 25 and k+25 ...
*February 23, 2014*

**Math**

isn't profit = revenue - cost ? plug in those values, simplify, then use either of the methods I just showed you in your previous post
*February 23, 2014*

**Math**

So in effect you are finding the vertex of the downwards opening parabola shortest way: the x of the vertex is -b/(2a) = -8/-.8 = 10 when x = 10 N(10) = -.4(100) + 8(10)+11 = 51 The ticket sales will peak at day 10 and on that day 51 tickets are sold method 2: complete the ...
*February 23, 2014*

**business finance**

so you are financing 55000 - 15000, or 40000 so let the monthly rate be i 1050(1 - (1+i)^-60)/i = 40000 payment = 40000/( 1 - (1+i)^-60)/i checking for some interest rates let i = 0, (no interest) payment = 40000/60 = 666.67 let i = .005 , (6% interest) payment = 40000/ (1 - 1...
*February 23, 2014*

**maths**

Ohh dear! midpoint is a "point" so it must look like ( ? , ? ) your method should be the x of the midpoint is (6+0)/2= 3 the y of the midpoint is (6-2)/2 = 2 so the midpoint is (3,2) (notice that in effect we are taking the average of the x's and the average of ...
*February 23, 2014*

**maths**

gradient = slope = (6-(-2))/(6-0) = 8/6 = 4/3 since (0,-2) is the y-intercept or the b of the y = mx + b notation, we can simply write y = (4/3) - 2 surely you have 2 little formulas in your text or your notebook to find the midpoint and the length. Let me know what you get.
*February 23, 2014*

**Math**

y = 4x^2 + 1 dy/dt = 8x dx/dt when x = 2, dy/dt = 1/2 sub that in.... 1/2 = 16 dx/dt dx/dt = 1/32
*February 23, 2014*

**Precalculus**

I was the one that answered you before when you had the typo (you had S instead of A for the short-tailed mice) and I actually found my scrap piece of paper where I made my Venn diagram. so.... My Venns agree with your data, and n(M' union S) = n(non male) + n(short tailed...
*February 23, 2014*

**Math**

I am going to assume that the kitchen and the dining room have the same width. so the length of large rectangle is x+12 and the width is x so x(x+12) = 589 x^2 + 12x = 589 x^2 + 12x + 36 = 589+36 (x+6)^2 = 625 x+6 = ± √625 = ± 25 x = -6 + 25 or -6-25 , the ...
*February 23, 2014*

**math**

put the decimal between the 1 and 4, then count the number of decimals it was moved from the end of the big number = 1.406 x 10^?? , you do the counting.
*February 23, 2014*

**math class**

f '(3) = 4 says that the slope is 4 when x = 3 f)3) = 9 means that you are dealing with the point (3,9) So they have given you the slope of the line and a point on it. I am sure you can take it from there.
*February 23, 2014*

**calculus**

What about it ?
*February 23, 2014*

**Math**

let x^2 - 18x - 4 = 0 best done by completing the square x^2 - 18x + 91 = 4 + 81 (x-9)^2= 85 x - 9 = √85 x = 9 ± √85 Your question should have said "What are the zeros of ...." , since there are two of them.
*February 23, 2014*

**math class**

The derivative should have been dy/dx = -3x^-4 = -3/x^4 when x = .5 or 1/2 dy/dx = -3/(1/2)^4 = -3/(1/16 = -3(16) = -48
*February 23, 2014*

**math**

first day he ran 1.5 2nd day he ran 1.5(1.1) 3rd day he ran 1.5(1.1)(1.1) = 1.5(1.1)^2 .. on the 7th day he ran 1.5(1.1)^6 so we have: 1.5 + 1.5(1.1)+ 1.5(1.1^2 + ... + 1.5(1.1)^6 which is a geometric series whose sum is 1.5( 1.1^7 - 1)/(1.1 - 1) = 1.5(.9487171)/.1 = 14....
*February 22, 2014*

**Pre-calculus**

your equation "falls apart" when p = 100 because you would be dividing by zero So mathematically, the cost would be infinitely large (that is, it is not possible) look at this graph and see what happens at p = 100 http://www.wolframalpha.com/input/?i=plot+C%3D80%...
*February 21, 2014*

**not Calculus Please help!**

B) compounded quarterly ----> i = .07/4 or .0175, and n = 6(4) or 24 amount = 7000(1.0175)^24 = $ 10,615.10 Do A and C the same way D amount = 7000 e^(6(.07)) = $ 10,653.73
*February 21, 2014*

**Calculus Please help!**

-8x + 4x dy/dx + 4y - 6y^2 dy/dx = 0 dy/dx(4x - 6y^2) = 8x - 4y dy/dx = (4x - 2y)/(2x - 3y^2) plug in x = 1 and y = 3 to find the slope
*February 21, 2014*

**Math**

Let the dimensions of the box by x by y by z xyz = 80 z = 80/(xy) "least amount of plasic" implies least surface area SA = 2xy + 2xz + 2yz = 2xy + 2x(80/(xy)) + 2y(80/(xy)) = 2xy + 160/y + 160/x now we know that xyz = 80 and 80 = (2)(2)(2)(2)(5) combinations of x y z...
*February 21, 2014*

**Math**

For simplicity sake, let's assume that the temperature increase is a linear function, (which it isn't), we would solve 2t + 20 = 98 2t = 78 t = 39 seconds
*February 21, 2014*

**Math! HELP!**

(3/2b^4)^3 = (27/8)b^12 (3/5y^4)^-2 = 1/(3/5y^4)^2 = 1/( (9/25)y^8 = 25/(9y^8) or (25/9)y^-8
*February 21, 2014*

**Algebra 1**

5x^2 + 2x^2 = 7x^2 (5 apples + 2 apples = 7 apples) Steve had a typo, happens even to the best of us
*February 21, 2014*

**Algebra 1**

Your question was answered , go back and check
*February 21, 2014*

**Intermediate algebra**

let number of AC adapters be x let number of flashlights be y 7x + 2y = 86 3x + 4y = 84 double the first equation 14x + 4y = 172 3x + 4y = 84 subtract them 11x = 88 x = 8 sub back into 1st: 7(8) + 2y = 86 2y = 30 y = 15 so 8 adapters and 15 flashlights. Check my answer to see ...
*February 21, 2014*

**Algebra 1 Answer Check**

1. correct if you meant 49^(3/2) The way you typed it --- 117649/2 2. can't read the question 3. the leading term in standard notation would be 8x^2 so leading coefficient is 8 4. correct 5. the x is undefined in your problem 6. 7x^2 - 2x + 5, the exponent is not affected ...
*February 21, 2014*

**algebra**

Steve is right, go with x-8 ≥ 20
*February 21, 2014*

**algebra**

After trying to make sense of your garbled English, I would pick x-8 > 20
*February 21, 2014*

**algebra**

Visualize the candy cane made in the form of a paper cylinder. Cut the cylinder open, you will see that the "ribbon" around the candy cane or cylinder consists of 4 diagonals for 4 different rectangles. the height of each of those rectangles is 20/4 or 5 cm and the ...
*February 21, 2014*

**math help**

poorly written up you lost the ratio notation and lack the equal sign correct presentation: 18 : 0.6 = 180 : 6 = 30 : 1
*February 20, 2014*

**Math**

I suspect you mean (x+1)/(x-2) = 3/6 confirm before I proceed
*February 20, 2014*

**Algebra**

the first one is already factored, so how come you are stuck on it ? 2nd: get the equation = 0 then it factors quite easily 4a^2 - 11a + 6 = 0 and 9r^r - 30r + 21 = -4 have you not been taught some kind of a method to factor these kind of trinomials? A common method these days...
*February 20, 2014*

**Probability**

I will assume that you filled in the Venn diagrams correctly n(M upside down u W) ---> n(M and W) = 14 n(M' U S) ---> n(M' or S) Since S is the symbol used for the universal set, the count would be 49 P( both mice are short-tailed) --- where does the "both&...
*February 20, 2014*

**Algebra**

Yeahhh! you got it
*February 20, 2014*

**Algebra**

4x^2 - 8x - 12 + 6x , looks like grouping works nicely = 4x^2- 8x+ 6x - 12 = 4x(x-2) + 6(x-2) = (x-2)(4x+6) = 2(x-2)(2x+3) 144 - 9p^2 , should have recognized difference of squares = (12-3p)(12+3kp) 5c^2 - 24cd - 5d^2 if it factors it must start with (5c ...)(c...) and end ...
*February 20, 2014*

**Algebra 1 (Reiny)**

Perimeter = 2s^3+4 + 5s + 4s^2 + 1 = 2s^3 + 4s^2 + 5s + 5 Why was this question difficult for you? If you are given the three sides of a triangle, wouldn't you just add them up to find the perimeter ?
*February 20, 2014*

**Math**

6x-2 = 3x+1 OR 6x-2 = -3x - 1 3x= 3 OR 9x = 1 x = 1 OR x = 1/9
*February 20, 2014*

**Math**

Mandy ---- b jay ------- b-3 kareem --- 2b look at my definitions,
*February 20, 2014*

**Algebra**

#1 should be -3x^2 + 5x- 12 #2 3x^2+ 5x - 6x - 10 = 3x^2- x - 10 #3, good, yeahhh #4, -2p^2 + 27p #5, yeahhh #6 good grief!!! = 2m^3 + 4m^2 + 8m - 4m^2 - 8m - 16 = 2m^3 - 16 #7, correct
*February 20, 2014*

**math**

let f(x) = ax^4 + bx^2 + c f(-1) = 0 , since it is a factor but f(-1) = a+ b + c so a+b+c = 0
*February 20, 2014*

**advanced functions**

-2t^3+3t^2+149t+410 = 980 2t^3 - 3t^2 - 149t + 570 = 0 could try 1, 2, 3, 4, 5 ,6, 7, 8, 9 ,10 Well, what do you know, t=5 works and so does t = 6 so there has to be 3 factors, I know the first two are (t-5)(t-6)(? t + ?) = 0 by the "common sense" theorem, the third ...
*February 20, 2014*

**Algebra**

see http://www.jiskha.com/display.cgi?id=1392932194
*February 20, 2014*

**Algebra**

If you meant y = -7/(x-16), then the domain is any real number, x ≠ 16 and for every x you pick there is one and only one value of y , except x=16 so it is a function.
*February 20, 2014*

**Algebra**

5y = 2x + 9 y = (2/5)x + 9/5 or y = (2x + 9)/5 now write f(x) = ... either of the two versions, both are correct
*February 20, 2014*

**Math Algebra**

Nice, that's the way I would do it,
*February 20, 2014*

**Algebra**

1/A + 1/B + 1/C = 3400 , #1 1/A + 1/B = 1900 (A+B)/(AB) = 1900 1900AB = A+B 1900AB - B = A B(1900A - 1) = A B = A/(1900A - 1) , #2 1/A + 1/C = 2300 A+C = 2300AC ... C = A/(2300A - 1) , #3 SUB #2 and #3 into #1 1/A + 1/(A/(1900A - 1)) + 1/A/(2300A - 1)) = 3400 1/A + (1900A - 1...
*February 20, 2014*

**Algebra**

just plug in k where you see an x
*February 20, 2014*

**Algebra**

done here http://www.jiskha.com/display.cgi?id=1392928082
*February 20, 2014*

**Algebra**

large frames ---- x small frames ---- 20-x 16x + 7(20 - x) = 176 solve, should be very straightforward
*February 20, 2014*

**math**

Pop(t) = 865 (1.15)^t , where t is the number of years
*February 20, 2014*

**Pre algebra**

There is no "answer" to y = 5x + 5 Your equation is represented by the graph of a straight line. The y-intercept is 5 , or the point (0,5) The x-intercept is -1 or the point (-1,0) Join these two points with a straight line and extend them in both directions. see: ...
*February 20, 2014*

**Math**

umhhh, Kimberly's age : Halley's age = 3 : 1 or 3/1
*February 20, 2014*

**MATH 12**

ahhh, just tried it again without the "solve" http://www.wolframalpha.com/input/?i=8500%281%2B12x%29%5E34+%2B+200%28+%281%2Bx%29%5E408+-+1%29%2Fx+%3D+193215.33 and got x = .0031041 or i = .0031041 12i = .0372492 So the equivalent annual rate of return for his ...
*February 20, 2014*

**MATH 12**

So I will assume a total time of 34 years or 408 months amount 30 years from now = 8500(1.0545)^34 + 200( 1.0025^408 - 1)/.0025 = 51641.968 + 141573.33655 = $ 193215.33 b) is quite complicated. Let the monthly return be i then 8500(1+12i)^34 + 200( (1+i)^408 - 1)/i = 193215.33...
*February 20, 2014*

**math**

a) amount = 8000 e^(12(.02)) = 8500 e^.24 = $ 10805.62 repeat procedure for the others
*February 20, 2014*

**math**

a) amount = 3500 e^(3(.0625)) = ..... same for the others.
*February 20, 2014*

**Math**

I suspect you mean: n(t)=5600/(0.5+27.5e^-0.044t) confirm my assumption before I proceed.
*February 20, 2014*

**College Algebra**

PV = 100000( 1 + .08/12)^-60 = 100000( 1.0066666..)^-60 = ...
*February 20, 2014*

**math**

2300 ----> 4600 after 1 decade so, once more gives you ??? I think your question is the incomplete version of this one, which was answered by Steve http://www.jiskha.com/display.cgi?id=1358452964
*February 20, 2014*

**Finance**

Assume an investment of $1.00 First Simple Bank: amount after 6 years = 1 + PRT = 1 + 1(.06)(10) = 1.60 Complex Bank: 1(1+i)^10 = 1.6 take 10th root of both sides ( (1+i)^10)((1/10) = 1.6^(1/10) 1+i = 1.048122.. i = .048122.. or appr 4.81%
*February 19, 2014*

**Finance**

32000 = 620 + 620( 1 - (1+i)^-59)/i My favourite webpage, Wolfram, says http://www.wolframalpha.com/input/?i=32000+%3D+620+%2B+620%28+1+-+%281%2Bx%29%5E-59%29%2Fx i = .0052576 or 12i = .06309 which is 6.309% per annum , compounded monthly (look past all that messy output to ...
*February 19, 2014*

**Algebra**

volume of 15% OJ --- x L volume of 10% OH --- 5-x L .15x + .1(5-x) = .11(5) times 100 , don't like them decimals! 15x + 10(5-x) = 55 15x + 50 - 10x = 55 5x = 5 x = 1 So 1 L of the 15% stuff and 4 L of the 10% stuff
*February 19, 2014*

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