Sunday

November 29, 2015
Total # Posts: 31,850

**Math**

why not just take the √ of both sides as it stands (x-2)^2 = 49 x-2 = ± 7 x = 2 ± 7 = 9 or -5 you had x^2 - 4x - 45 = 0 which would have factored to (x-9)(x+5) = 0 x = 0 or x = -5
*August 12, 2015*

**Calculus**

draw a right-angled triangle (side view) mark the base as 80, and the height of the balloon as h a) you want to know how fast the balloon is receding, so we are talking about how fast the hypotenuse is changing. let the hypo be x x^2 = 80^2 + h^2 2x dx/dt = 0 + 2h dh/dt, but ...
*August 12, 2015*

**Calculus**

http://www.jiskha.com/display.cgi?id=1439263714
*August 12, 2015*

**algebra 2**

I find that changing everything to sines and cosines usually works well for these type of problems unless you recognize one of the standard formulas. LS = sin^2 x (1 + cos^2 x/sin^2 x) = sin^2 x (sin^2 x + cos^2 x)/sin^2 x , forming a common denominator = sin^2 x (1/sin^2 x...
*August 11, 2015*

**@ Steve - Math**

I ain't touching that one :)
*August 11, 2015*

**Maths**

Make a sketch. the line from the centre hits the chord at its midpoint and you have a right-angled triangle. You can use Pythagoras. r^2 = 3.3^2 + 5.6^2 = 42.25 r = √42.25 = 6.5
*August 11, 2015*

**math**

The way your question is worded makes no sense You must have meant this: done by Steve last year http://www.jiskha.com/display.cgi?id=1397894767
*August 11, 2015*

**eua high school**

surface area of a graph???
*August 11, 2015*

**Calculus**

done, look at your previous post
*August 11, 2015*

**calculus**

to be at rest, v = 0 4t^2 - 1 = 0 4t^2 = 1 t^2 = 1/4 t = 1/2 let the displacement be s s = (4/3)t^3 - t + c assume that when t = 0 , s=0 , then c =0 s= (4/3)t^2 - t when t = 1/2 s = (4/3)(1/4) - 1/2 = 1/3 - 1/2 = -1/6 the object is 1/6 m to the "left" of O
*August 11, 2015*

**Calculus**

y = 1 - cos^2 x y = 1 - (cos x)^2 dy/dx = -2cosx (-sinx) = 2 sinx cosx or sin (2x)
*August 11, 2015*

**yale high school**

your number when divided by 4 leaves a remainder of 3 when divided by divided by 5, leaves a remainder of 2 numbers which fit the first case: 7 11 15 19 23 27 31 35 39 numbers which fit the 2nd case: 7 12 17 22 27 the least number would be 7, but I have a feeling they are ...
*August 11, 2015*

**math**

your equation factors to (w-4)(2w + 13) = 0 so w = 4 or w = -13/2, which makes no sense so the width is 4 and the length is 2(4) + 5 or 13
*August 11, 2015*

**please help urgent**

For your second, the 15-year plan i = .0775/12 = .00645833.. n = 15(12) = 180 p( 1 - 1.00645833^-180)/.006458333 = 300000 I got p = 2823.83 you had the same, good job As to your last question, you cannot just add up the payments. e.g. a payment of $500 made today does not have...
*August 10, 2015*

**please help urgent**

I will do the first, you do the 2nd i = .085/12 = .00708333.. n = 30(12) = 360 payment = p PV = p(1 - (1+i)^-n)/i 300000 = p(1 - 1.00708333^-360)/.007083333) 300000 = p(130.0536..) p= 2306.74
*August 10, 2015*

**Maths**

I don't know your notation of 100/-
*August 10, 2015*

**Urgent math**

This is an arithmetic series where a = 40000 , d=1900 you want sum(10) sum(10) = (10/2)(2(40000) + 9(1900)) = 485500 What you found is how much he made in the 11th year.
*August 10, 2015*

**Calculus**

make a sketch let the distance of the man from the lamp-post be x let the length of his shadow be y by ratios: 5.5/y = 10/(x+y) 5.5x + 5.5y = 10y 5.5x = 4.5y times 10 55x = 45y 11x = 9y 11 dx/dt = 9 dy/dt 11(8) = 9 dy/dt dy/dt = 88/9 ft/s or 9 7/9 ft/s --> rate at which the...
*August 10, 2015*

**Math**

Did you post this question under the name of Fay? http://www.jiskha.com/display.cgi?id=1439188422 a(1) = 1 a(2) = 3 a(1) + 6 = 3(1) + 6 = 9 a(3) = 3 a(2) + 6 = 3(9) + 6 = 33 a(4) = 3 a(3) + 6 = 3(33) + 6 = 105 a(5) = 3 a(4) + 6 = 3(105) + 6 = 321
*August 10, 2015*

**Calculus**

What about it ?
*August 10, 2015*

**Math**

It should be clear to you that the 37.313 is the number of quarter years, and if I divide that by 4 I would get years 37.313../4 = 9.33 years rounded to 2 decimal places
*August 10, 2015*

**Math**

i = .075/4 = .01875 1. n = 4(3) = 12 amount = 3000(1.01875)^12 = 3749.15 2. 3000(1.01875)^n = 6000 , where n is the number of quarter years 1.01875^n = 2 take logs of both sides and use use of logs n log 1.01875 = log 2 n = log 2/log 1.01875 = appr 37.313 = 37.313../4 or appr ...
*August 10, 2015*

**Algebra**

7% = .07 , not .7 like you had That was your major mistake. a) equation: n(t) = 1900 e^(.07t) b) if 2005 ---> t = 0 then 2010 ---> t = 5 n(5) = 19000 e^(.07*5) = 26962 I don't understand how you could possible think that 5 foxes would be correct. there were 19000 ...
*August 10, 2015*

**logarithms maths**

Nothing to solve, I don't see an equation Are you simplifying? Do you mean log x + log(x+n) - log(x/n) ??? Do you know your basic rules of logs ? if so, then log x + log(x+n) - log(x/n) = log( x(x+n)) - (logx - logn) = log( x(x+n) - logx + logn = log( x(x+n)(n)/x) = log( n...
*August 10, 2015*

**Math sequences**

you have a geometric series with a = 1 and r = 4/5 sum(n) = a(1 - r^n)/(1-r) > 4.9 1(1 - (4/5)^n)/1/5 > 4.9 1 - (4/5)^n > .98 (4/5)^n < .02 suppose we let .8^n = .02 log .8^n = log .02 n = log.02/log.8 = 17.53 testing: if n = 17 , sum(17) = (1 - .8^17)/.2 = 4.8874...
*August 10, 2015*

**statistics and probability**

-2(y-3)= 5y-29 -2y + 6 = 5y - 29 -7y = -35 y = 5
*August 10, 2015*

**a math**

For this to work you must mean (cotx-1)/(cotx+1) = sec(2x) - tan(2x) LS = (cosx/sinx - 1)/(cosx/sinx +1) multiply top and bottom by sinx = (cosx - sinx)/(cosx + sinx) RS = 1/cos(2x) - sin(2x)/cos(2x) = (1 - 2sinxcosx)/(cos^2 x - sin^2 x) = (sin^2 x + cos^2 x - 2sinxcosx)/((...
*August 10, 2015*

**calculus**

height of balloon = -16t^2 + 15t + h 0 = -16(8^2) + 15(8) + h h = .....
*August 10, 2015*

**good grief !!! - sets, maths**

Just realized looking at the Related Questions below, that I answered this same question for you back in July of this year. What gives ????
*August 10, 2015*

**sets, maths**

I assume you did this with Venn diagrams We don't know how many watch all three, label that x look at the intersection of the hockey and Football circles, it says 70 watch both but we already have x accounted for, so place 70-x in the part showing only hockey and football ...
*August 10, 2015*

**critical probability**

E D W A as a 3-letter "word" = 4x4x4 = 64 ways if the letters can be repeated and 4x3x2 or 24 ways if the letters cannot be repeated.
*August 10, 2015*

**word problem urgent**

amount = intitial amount (1/2)^(t/6), where t is hours and initial amount = 255 from 8:00 to 11:30 = 3.5 hours from 8:00 to 4:00 pm = 8 hours a) at 11:30, t = 3.5 amount of caffeine = 255(1/2)^(3.5/6) =170.192 b) at 4:00 amount = 255(.5)^(8/6) = 101.1968 she drinks another ...
*August 10, 2015*

**Algebra**

same question as the previous one, let me know what you got
*August 10, 2015*

**Algebra**

i = .09/12 = .0075 n =9(12) = 108 cash value of car = 4000 + 260(1 - 1.0075^-108)/.0075 = ...
*August 10, 2015*

**Arithmetic**

did you recognize the series as a geometric series with a = 1 and r = -1/2 ?? If you are studying this topic you MUST know the formula for the sum of n terms hint: how many terms are there ? look at this patters term(2) = -1/2 = -1/2^1 term(3) = 1/4 = +1/2^2 term(4) = -1/8 = -...
*August 10, 2015*

**Urgent math**

using the standard notation of a and d, a = 5 a+4d = 6.5 then 5 + d = 6.5 d = 1.5 sum(15) = (15/2)(2(5) + 14(1.5)) = 232.5
*August 10, 2015*

**Urgent math**

5 consecutive problems from a variety of topics Sure looks like a home-work dump or you expect us to do some kind of assignment for you. Show some work and let me know where you got stuck on the others.
*August 10, 2015*

**Urgent math**

I am sure you meant: an = 3a(n-1) + 6 in this notation , given any an an-1 would be the previous term. so if a1 = 1 then a2 = 3a1 + 6 = 3(1) + 6 = 9 a3 = 3a2 + 6 = 3(9) + 6 = 33 continue building them that way.
*August 10, 2015*

**math**

speed of slower car --- x mph speed of faster car ---- (4/3)x they both went for 6 hours 6(4/3)x - 6x = 90 8x - 6x = 90 2x = 90 x = 45 mph slower car: 45 mph faster car: 60 mph
*August 10, 2015*

**math**

speed of plane in still air --- x mph speed of wind ------ y mph rate into the wind = x-y rate with the wind = x+y 2(x+y) = 540 x + y = 270 3(x-y) = 690 x-y = 230 add them: 2x = 500 x = 250 then y = 20
*August 10, 2015*

**math**

I have now done 3 questions for you. How about you doing this one ?
*August 10, 2015*

**Math**

with some simple button-pushing on my calculator, I got ± .92052528
*August 10, 2015*

**Math**

It is always a good idea to check your typing for spelling and gammar, that way we don't have to second-guess what you mean. let the amount of her money be x she spent 1/3 x on the wallet, leaving her with (2/3)x She spent (1/4) of that on a belt she spent (1/4(2/3)x = (1/...
*August 9, 2015*

**Kaputian samal Central**

since the number is between 15 and 25, it must start with a 1 or a 2 case1: it starts with a 1 since the sum of the digits is 5, the unit digit is 4, making the number 14. But it has to greater than 15. So that case is out. case2: it starts with a 2 then the other digit is 3 ...
*August 9, 2015*

**Trig**

cos 13π = cos( 4(2π) + π) , 13π is 4 rotations + π = cosπ = -1
*August 8, 2015*

**algebra 1**

x^2 + 2x + 1 = 1 - x x^2 + 3x = 0 x(x+3) = 0 looks like two solutions
*August 8, 2015*

**Math**

surface area of the pen = 2πrh = 2πr(5) = 10πr square feet but each square foot costs $1 so cost = 10πr 10πr = 1000 r = 1000/(10π) = appr 31.8 ft They should not have rounded 31.8 up to 32 ft, since at 32 ft, the cost would have been 2π(32)(5...
*August 8, 2015*

**Math**

x+y = 90 y = 90-x siny = sin(90-x) = cosx = 4/5 the sin( of any angle) = cos(of its complement) the fact that sinx = 3/5 was a distraction and did not have to be given.
*August 8, 2015*

**Math**

x/(π/6) = 36/2π x = (π/6)(36/(2π)) = 3 in^2
*August 8, 2015*

**math**

should be: n(n+1)(2n+1)/6 Do you know induction?
*August 8, 2015*

**algebra i**

yes, you have a typo in your second equation, forgot the t
*August 8, 2015*

**Maths**

seats with 2 on them --- x seats with 3 on them --- y x+y = 7 --- y = 7-x 2x + 3y = 20 2x + 3(7-x) = 20 2x + 21 - 3x = 20 -x = -1 x = 1 1 seat with 2 kids, 6 seats with 3 kids (totally illegal where I live)
*August 8, 2015*

**algebra**

shade in the region to the right of x = 5
*August 8, 2015*

**algebra**

or 2y ≥ -3x - 10 y ≥ (-3/2)x - 5 sketch y = (-3/2)x - 5 then shade in everything above the line
*August 8, 2015*

**Math**

number of bikes --- b number of trikes--- t (assume: a bike has 2 pedals and 2 wheels, a trike has 2 pedals and three wheels) 2b+2t = 80 --- > b = 40-t 2b + 3t = 98 2(40-t) + 3t = 98 80-2t+3t=98 t=18 b = 22 He has 22 bikes and 18 trikes
*August 8, 2015*

**Maths I NEED AN ANSWER ! THE 6 IS ALL I KNOW!!!**

Your 5th sentence suggests that it is a 3-digit number, and we also know all digits are even. so far you know: -6- it says the greatest is in the one's place and must be even. Well, since the only even greater than 6 is 8 we now have: -6 8 and we also know that the sum is ...
*August 8, 2015*

**math**

If the | ...| means absolute value, then x^2 - 16x + 56 = -4x-7 or -x^2 + 16x - 56 = -4x - 7 case1: x^2 - 12x + 63 = 0 complete the square: x^2 - 12x + 36 = -63 + 36 (x-6)^2 = -27 no real solution, I have not seen complex numbers associated with absolute value case2: -x^2 + ...
*August 8, 2015*

**algebra**

the t of the vertex is -b/(2a) = -96/(-32) = 3 so t = 3 is the axis of symmetry btw, your function should have said f(t) = -16t^2 + 96t, there was no x in sight.
*August 7, 2015*

**Area**

divide 19 by .04
*August 7, 2015*

**Geometry**

The sum of any two sides has to be greater than the third side If third side is 2 from A then 2+3 is not greater than 5 so A
*August 7, 2015*

**PS - Math**

I sure hope that the above is not how "they" are teaching you to calculate simple interest
*August 7, 2015*

**Math**

I = k(P)(T) , compare with I = PRT, so k is jus like the rate R given: when P = 3000, T=6, then I = 1260 1260 = k(3000)(6 k = 1260/( (3000)(6) ) = .07 , mmhhh, looks like we just found the interest rate I = .07(P)(T) so for the last part I = .07(3000)(7) = 1470
*August 7, 2015*

**Math**

I = k (1/d^2) given: when I = 70, d = 5 70 = k/25 k = 1750 so I = 1750/d^2 when d = 4 I = 1750/4^2 = 109.375
*August 7, 2015*

**Math**

R = k(1/T) = k/T when R = 60, T = 8 60 = k/8 k = 480 R = 480/T so when T = 6 R = 480/6 = 80 mph
*August 7, 2015*

**Mth 156**

x(1.015)^24 = 35000 x = 24484.04
*August 7, 2015*

**math**

correct
*August 7, 2015*

**Math-manipulation of the formula**

(1+i)^n = A/P 1+i = (A/P)^(1/n) i = (A/P)^(1/n) - 1
*August 7, 2015*

**math**

shorter of the other sides --- x longer of the other sides ---- 2x To be a triangle the sum of any two sides must be greater than the third side x+2x > 17 AND x+17>2x AND 2x+17>x 3x > 17 AND x < 17 AND x > -17 x > 17/3 AND x < 17 (x is between 5.666.. ...
*August 6, 2015*

**oops - math**

I have to read the question more carefully. It clearly said 10 months and I used 12 months so let's just make a simple change (1+i)^10 = 1.15625 take the 10th root 1+i = 1.15625^(1/10) 1+i = 1.014624.. i = .014624 annual rate = 12(.014624) = .1755 or appr 17.55%
*August 6, 2015*

**math**

let the monthly rate be i 3200(1+i)^12 = 3700 (1+i)^12 = 1.15625 take 12th root 1+i = 1.01217.. i = .01217.. annual rate compounded monthly = .14606 or appr 14.6%
*August 6, 2015*

**algebra**

(73+x)/2 = 81 73+x = 162 x = 89
*August 6, 2015*

**Calculus 1**

For you to say that you have no clue how to start this straightforward question is not a good sign if you are in a Calculus course. by Calculus, take vertical discs of width dx and height 2x+1 V = π ∫ r^2 dx V = π∫(2x+1)^2 dx from 0 to 1 = π [ (1/6)(...
*August 6, 2015*

**math**

first of all, for a + 1/a to be equal to 6, a would not be a "nice" number we could find it .... a + 1/a = 6 multiply each term by a a^2 + 1 = 6a a^2 - 6a + 1 = 0 a = (6 ± √32)/2 = 3 ± 2√2 , not nice as predicted we could square that, and ...
*August 6, 2015*

**math**

I will assume you mean 2003^(x^2 + 2x - 35) = 1 then 2003^(x^2 + 2x - 35) = 2003^0 thus: x^2 + 2x - 35 = 0 (x+7)(x-5) = 0 x = -7 or x = 5 and the product of those two x's is -35
*August 6, 2015*

**math**

if 3^a = 2 then 9^(4a) = (3^2)^(4a) = (3^a)^8 = 2^8 49^(2b) = (7^2)^(2b) = (7^b)^(4) = 5^8 then 9^4a * 49^2b = (2^8)(5^4) ------> C
*August 6, 2015*

**math**

I can only see (0,5) and (-5,0) the right side has to be a perfect cube so it could be 1,8,27,64,125, 216 which means that a^3 + 125 must be one of those numbers, and a^3 would be one of those : 124, 117, 98, ... does not look too promising other than the 2 I stated
*August 6, 2015*

**Trigonometry**

make your sketch drop an altitude from the plane to the ground to get 2 right-angled triangles let the height of the plane be h let the base of the 11° triangle be x then the base of the other triangle is 2-x from the 11° triangle: tan11 = h/x --->h = xtan11 from ...
*August 5, 2015*

**algebra**

volume = x(x+2)(x+6) expand it, if there is need to do so.
*August 5, 2015*

**statistic**

This webpage is perfect for your type of question. Just enter the data http://davidmlane.com/hyperstat/z_table.html
*August 5, 2015*

**Math**

short side --- x diagonal --- x+8 other side --- y x^2 + y^2 = (x+8)^2 x^2 + y^2 = x^2 + 16x + 64 y^2 = 16x + 64 y = √(16x+64) area = xy = 60 x√(16x+64) = 60 square both sides x^2(16x+64) = 3600 16x^3 + 64x^2=3600 x^3 + 4x^2 - 225 = 0 looks like x = 5 works then y...
*August 5, 2015*

**Math**

yes
*August 5, 2015*

**alg1**

8m^2 +20m=12 8m^2 +20m-12=0 divide each term by 4 2m^2 + 5m - 3 = 0 (2m - 1)(n + 3) = 0 m = 1/2 or m = -3
*August 5, 2015*

**math**

The lengths of the arms or rays that form an angle have nothing to do with the size of the angle they form e.g. sketch any angle. Now extend the rays that form the angle. Did anything happen to the angle ??
*August 5, 2015*

**maths**

anonymous made the "lucky" assumption that the second fraction ?/x^2 had a constant for a numerator. In general you cannot make such an assumption. If the denominator is a second degree expression, like x^2, then the numerator could be a first degree expression of ...
*August 5, 2015*

**maths**

You fixed Damon's concern, but still brackets are missing I will assume you meant: (x^3+6)/(x^2(x+3) ) I first did a long algebraic division to get it to 1 - (3x^2 - 6)/(x^2(x+3) ) So let's just work on that last term let (3x^2 - 6)/(x^2(x+3) ) = A/x + (Bx + C)/x^2 + D...
*August 5, 2015*

**mathematical**

Now: father ---- x Robin ---- x-25 after 10 years: father = x+10 Robin = x-25 + 10 = x-15 (x-15)/(x+10) = 1/2 2x - 30 = x+10 x = 40 state your conclusion
*August 5, 2015*

**math**

Saw this same question the other day. Is there a reason why you are using square brackets and round brackets? Is it simply (428)(-23)+(-428)(-223) ? If so, I am sure you have a calculator. remember for the order of operation, the multiplication has to be done before the addion.
*August 5, 2015*

**Calculus**

dy/dx = 2x which is the slope of the tangent at any point (x,y) on the parabola so at (1,2) , the slope of the tangent is 2(1) = 2 since the normal is perpendicular to the tangent, the slope of the normal must be -1/2 equation: y-2 = (-1/2)(x-1) you can doctor that up any way ...
*August 5, 2015*

**Calculus**

did this one yesterday http://www.jiskha.com/display.cgi?id=1438682725
*August 4, 2015*

**Algebra**

you will need a slope of -1/m so clearly false.
*August 4, 2015*

**Calculus**

x = 3 and y^2 = 12x intersect at (3,6) and (3,-6) so we can take horizontal slices, and because of the symmetry just go from y = 0 to y = 6 and double the result. we also have a radius of 3 - y^2/12 V = 2π ∫r^2 dy from 0 to 6 = 2π ∫(3 - y^2/12)^2 dy from ...
*August 4, 2015*

**calculus**

assuming a = -32 and seeing that the initial velocity was -15 from a height of 904, I know s = -16r^2 - 15t + 904 we want s = 0 16t^2 + 15t - 904 = 0 won't waste time trying to factor it ... t = (-15 ± √58081)/32 = (-15 ± 241)/32 ----- ahh, it does ...
*August 4, 2015*

**calculus**

welcome, hope you checked my arithmetic
*August 4, 2015*

**calculus**

ok, then a = t^(-3/2) v = -2 t^(-1/2) + c s = -4 t^(1/2) + ct + k case1: s=8, when t = 1 8 = -4 + c + k 12 = c + k case2: s = 16, when t = 4 16 = -4(2) + 4c + k 24 = 4c + k subtract them: 12 = 3c c = 4 back in 12 = c+k 12 = 4+k k = 8 then v = -2/√t + 4 when t = 9 v = -2/...
*August 4, 2015*

**calculus**

do we have a = 1/(t√t) or is it a = (1/t)√t ??
*August 4, 2015*

**Probability**

Consider the elf and the dwarf as one item, so you are now arranging 4 which is 4! or 24 but we can switch the elf and the dwarf and still have them side by side, so 2(4!) = 48
*August 4, 2015*

**math**

so the year can't have any zeros smallest possibe = 1911 largest is 1999 since they all have to start with 99, variations of products can only come from the last 2 digits 1914 1941 1922 all produce the same product 1942 1924 1918 1981 all produce the same product same ...
*August 4, 2015*

**math**

look for an exception, that way we can rule out the choice which does not work e.g. x = 500 √516 = appr 22.7 A) is 22.7 between 22.36 and 22.38 , no B) is 22.7 between 22.38 and 22.4 , no I will stop here, since the question does not make any sense to me no matter what ...
*August 4, 2015*

**math**

smallest n = 2 n = 2 ---> 2,4,6 nope n = 3 ---> 3,5,7 YES n = 5 ---> 5,7,9 nope n = 7 ---> 7,9,11 nope n = 11 ---> 11,13,15 nope .. n = 23 --> 23, 25, 27, nope Other than 2, all primes are odd so we need 3 sequential odd numbers to have the above property BUT...
*August 4, 2015*

**math**

(±3,±4) that's 4 of them (±4,±3) that's 4 more (0,±5) 2 more (±5,o) and 2 more I count 12
*August 4, 2015*