Thursday

February 11, 2016
Total # Posts: 32,937

**maths**

15x + 12(10-x) = 141 solve for x to get the amount sold at 15
*January 25, 2016*

**math**

volume of block of paper = (11)(8.5)(2) in^3 = 187 in^3 so volume of 1 sheet = 187/500 or .374 inches^3
*January 25, 2016*

**maths**

Steve gave you the two equations, so use substitution. y = x + 15 x+y = 275 sub 1st into 2nd x + (x+15) = 275 2x = 260 x = 130 back into y = x+15 y = 130+15 = 145
*January 25, 2016*

**Algebra**

yup, the sum of cubes.
*January 24, 2016*

**College algebra**

let the distance driven be x km speed on first leg = x/8 speed on return leg = x/8 + 18 km/h = (x + 144)/8 km/h distance/rate = time x/((x+144)/8) = 5 8x/(x+144) = 5 8x = 5x + 144 3x = 144 x = 48 so speed on return trip = (48+144)/8 km/h = 24 km/h
*January 24, 2016*

**algebra**

That is an example change to ... x+31 > 5 x > -26 shade in everything to the right of the vertical line x = -26 , draw the line as a dotted line.
*January 24, 2016*

**math**

or, using the compound interest formula (1 + i)^74 = 3 , where i is the quarterly rate take 74th root of both sides 1+i = 1.01495.. i = .01495.. annual rate compounded quarterly = 4(.01595..) = .0598 or 5.98%
*January 24, 2016*

**trig**

My triangle has sides 60 , 20 and 50 km and I am finding the angle opposite the side of 50 by cosine law: 50^2 = 20^2 + 60^2 - 2(20)(60)cosØ cosØ = .625 Ø = appr 51.3°
*January 24, 2016*

**oops - Calculus**

go with Damon's I really don't know how my 1/√2 became 1/√3
*January 24, 2016*

**Calculus**

I recognize this as Lim ( 1/3 - 1/√x)/(x-9) , as x -->9 But for yours x --->2 Most teachers would tell you that the first step in any limit question is to actually sub in the restricted value into your expression. If you get 0/0, then you have some work to do If ...
*January 24, 2016*

**Math**

This is pretty "advanced" stuff Your nail traces out a cycloid, the equation of that path can be written as parametric equations x=r(t−sint) y=r(1−cost) , where t is the angle of rotation, and r is the radius What level of math is this ? http://mathworld....
*January 24, 2016*

**maths**

(1/2)(12)height = 38.8 height = 97/15 or 6.466.. assuming your base is BC sin 54° = height /AC AC = height/sin54° take over
*January 24, 2016*

**ggggg**

smallest angle --- x one of the others --- 2x third angle = x+2x = 3x thus: x + 2x + 3x = 180 carry on
*January 24, 2016*

**MTH**

Did you mean (x+y)^25 ? Do you really expect me to write out all 26 terms ? What is "the porem" ?
*January 24, 2016*

**correction - math**

So you have two ordered pairs: (30,2) and (50,6) slope = (6-2)/(50-30) = 4/20 = 1/5 equation: y-2 = (1/5)(x-30) 5y - 10 = x - 30 x - 5y = 20 ----> that's your relationship then if y = 3, x - 15 = 20 x = 35
*January 24, 2016*

**maths**

r = 6/(3-x) OR r = (7-5x)/6 6/(3-x) = (7-5x)/6 21 - 15x - 7x + 5x^2 = 36 5x^2 - 22x - 15 = 0 (x - 5)(5x + 3) = 0 x = 5 or x = -3/5 so the common ratio could be 6/3-5) = -2 or 6/(-3/5) = -10 if r = -2, we have -3 + 6 - 12 = -9 if r = -10 , we have -5/3 + 6 - 60 = - 167/3 check ...
*January 24, 2016*

**math**

let f(x) = ax + b then f(f(x)) = a(ax+b) + b = a^2 x + ab + b so a^2 = 64 ---> a = ±8 then ab+b=-21 b = -21/(a+1) if a=8 , b = -21/9 = -7/3 if a = -8, b = -21/-7 = 3 f(x) = 8x - 7/3 OR f(x) = -8x + 3 check: if f(x) = -8x + 3 f(f(x)) = -8(-8x+3) + 3 = 64x - 21 if f(x...
*January 24, 2016*

**Math**

let the annual rate be i 1+i = (1 + .024/12)^12 = 1.02426 i = .02426 or 2.426 % per annum The difference would be more significant for higher rates of interest.
*January 24, 2016*

**math**

I am the one that gave you the answer in your previous post. I am just using the formula for compound interest. Have you learned about compound interest?
*January 24, 2016*

**math**

Since we are "doubling" it is easy to use a base of 2 amount = a(2)^(t/1) = a (2)^t , where t ≥ 0, and t=0 ---> now after 1 day we have 2a after 3 days , we have a(2)^3 or 8a after 1 week , we have a(2)^7 = 128a normally we would use base e here we have ...
*January 24, 2016*

**math**

assuming your rate is compounded annually, what is 87000(1.045)^8 ?
*January 24, 2016*

**Maths**

My money is on Steve's correct answer.
*January 24, 2016*

**Math**

Did you make a sketch? The area reached by the horse is 1/4 of a circle with original radius of 6 m that area = (1/4)π(36) = 9π m^2 after lengthening of rope, r = 11.5 m new area for grazing = (1/4)π(11.5)^2 m^2 = 33.0625π m^2 So what is the increase in area ?
*January 24, 2016*

**math**

Filling in the given information in a Venn diagram, I got 8 taking all three subjects 7 taking only Chemistry 6 taking only Biology These were the only ones that required calculations, the rest were given. Adding up all the entries in the Venn diagrams only comes to 44, thus ...
*January 24, 2016*

**@ shredder - Maths**

Simply stating the answer serves the student no purpose.
*January 24, 2016*

**probstats**

number of possible codes = 9x10x10x10x10 = 90000 number starting with 7 and ending in 8 = 1x10x10x10x1 = 1000 prob(your event) = 1000/90000 = 1/90
*January 24, 2016*

**math/trigo**

Again, my money is on Steve's answer.
*January 24, 2016*

**math**

Make a sketch showing the trapezoid in a side view. Volume = (area of trap) x 8 = (13(2 + h)/2)(8) = 52(2+h) = 286 104 + 52h = 286 h = .....
*January 24, 2016*

**arthmetic sequence**

by definition: a+2d = 14 a+8d = -1 subtract ... 6d = -15 d= -5/2 then a+2(-5/2) = 14 a = 19 first 4 terms are 19, 33/2 , 14 , 23/2
*January 23, 2016*

**math**

by the cosine law: AC^2 = 8^2 + 24^2 - 2(8)(24)cos60° = 448 AC = √448 = 8√7 now by similar triangles: DE/8√7 = 6/8 DE = 48√7/8 = 6√7
*January 23, 2016*

**Algebra**

I agree with Bob
*January 23, 2016*

**Related Rates**

from your V= (1/3)π(r)(r)(h) , but r = h V = (1/3)π h^3 dV/dt = π h^2 dh/dt plug in the values .... 10 = π(25) dh/dt dh/dt = 10/(25π) = 2/(5π) I have no idea how you got your derivative.
*January 23, 2016*

**Math**

I will let you count the days --- d I = PRT = 4500(.08)(d/365)
*January 23, 2016*

**Maths**

that is .... 3000 cm = 30 m you wouldn't measure road distance in cm .
*January 23, 2016*

**math**

I am sure you made a sketch. Let the length of his shadow be x By similar triangles..... x/2 = (x+5)/6 6x = 2x+10 carry on
*January 23, 2016*

**Math**

amount of mortgage before raise = .23(6000) = 1380 after raise, rate = 1380/6500 = .2123 or appr 21.2%
*January 23, 2016*

**NO - Maths**

This is an inverse relation, not a direct proportion i.e. the more artists, the lesser the time "It takes 3 artists 24 days to paint a building" ---> 72 artist-days for 72 artist-days / 6 artists = 12 days
*January 23, 2016*

**algebra**

done when you posted this under a different name. look at your other post.
*January 23, 2016*

**Algebra**

What part of my solution to the same question did you not like ? http://www.jiskha.com/display.cgi?id=1453557228
*January 23, 2016*

**algebra**

just did it, look back
*January 23, 2016*

**algebra**

Your first question makes no sense your second: Tn = a + bn T6 = a + 6b = 22 T13 = a + 13b = 71 subtract them 7b = 49 b = 7 a+6b=22 ---> a + 42 = 49, a = 7
*January 23, 2016*

**math**

In triangle DRA, draw an altitude DK where K is on RA, to get a 30-60-90° triangle and you should know that the corresponding sides are in the ratio 1 : √3 : 2 So RK/(6√2) = √3/2 x = 3√6 then RA = 6√6 and the perimeter is 24√6
*January 23, 2016*

**maths**

rate of smaller tap = 1/45 tanks/min rate of larger tap = 1/30 tanks/min combined rate = (1/45 + 1/30) tanks/min = 1/18 tanks/min time at combined rate = 1/(1/18) min = 18 minutes
*January 23, 2016*

**math**

radius of flower bed --- r m 2πr = 66 r = 33/π radius of whole thing = 4+33/π area of whole thing = π(4+33/π)^2 area of flower bed =π(33/π)^2 subtract the two areas to get the area of the path. you do the arithmetic
*January 23, 2016*

**maths**

"product" is the result of a multiplication So if the product of 2 numbers is zero, one of them must have been zero since the difference is 6 , the other number must have been 6 Only choice possible for your number : 60
*January 23, 2016*

**math**

done ,see you other post
*January 23, 2016*

**Algebra**

the way you typed it: (x-2)+1/x+1=2/3 x-2 + 1/x + 1 = 2/3 x + 1/x -1 - 2/3 = 0 times 3x 3x^2 + 3 - 3x - 2x = 0 3x^2 - 5x + 3 = 0 x = (5 ± √-11)/6 no real solution You probably meant: x- 2 + 1/(x+1) = 2/3 times 3(x+1) 3x(x+1) - 6(x+1) + 3 = 2(x+1) 3x^2 + 3x - 6x - ...
*January 23, 2016*

**Maths**

my number is x result1 = 8x + 15 result2 = 2x + 81 so 8x + 15 = 2x + 81 can you solve this equation ? test your answer.
*January 23, 2016*

**math**

Surely for the 2nd equation Akbar must have meant: 2^(x+2)+3^(y+1)=5 or else why not just add up those constants. (2^2)(2^x) + 3(3^y) = 5 let a = 2^x and let b = 3^y, then we can reduce our equations to ... a+b = 17 4a + 3b = 5 first one by 3 3a + 3b = 51 4a + 3b = 5 a = -46 b...
*January 23, 2016*

**Algebra**

did you sub in the point ?
*January 22, 2016*

**math help pls pls**

actually it would be all the points above and including the line y = -3x+10 http://www.wolframalpha.com/input/?i=plot+y+%E2%89%A5+-3x%2B10+
*January 22, 2016*

**Math**

where are your choices so we can check ?
*January 22, 2016*

**check this - math**

Or using a property of quadratic roots: for ax^2 + bx + c = 0 if p and q are the roots p+q = -b/a qp = c/a so for the given equation: p+q = -6/-2 = 3 pq = -7/2 a) for new equation: roots are p/q and q/p sum = p/q + q/p = (p^2+q^2)/(pq) = ( (p+q)^2 - 2pq)/(pq) = (9 - 2(-7/2...
*January 22, 2016*

**Algebra 2 pt 2**

Damon did this for you here: http://www.jiskha.com/display.cgi?id=1453466988
*January 22, 2016*

**5th grade math**

The value of the 9 in 794256 is 9x10,000 or 90,000 the value of 9 in 12,276,459 is 9x1 and 90000/9 = 10,000 so isn't it 10,000 times the value ?
*January 22, 2016*

**Math**

width -- x length -- 3x so x^2 + (3x)^2 = (6√10)^2 10x^2 = 360 x^2 = 36 x = 6 finish it up
*January 21, 2016*

**Algebra**

Why not just translate all that English into Math Katie --- x Harry --- x+4 Rachel --- 2(x+4) x + x+4 + 2(x+4) = 36 take over
*January 21, 2016*

**math**

since the denominator can never equal to zero and it contains no square roots or other strange operators, domain : x ∊ R I like the "old fashioned" format I used, I always have to look up this "interval notation stuff" I will let you write it your way.
*January 21, 2016*

**Math**

f(1) = 1^3 - 3 = -2 f(1+h) = (1+h)^3 - 3 = 1 + 3h + 3h^2 + h^3 - 3 = h^3 + 3h^2 + 3h - 2 avg rate of change = (h^3 + 3h^2 + 3h - 2 + 2)/(1+h - 1) = (h^3 + 3h^2 + 3h)/h = h^2 + 3h + 3 , h ≠ 0
*January 21, 2016*

**Calculus**

f(t) = 1/t f(1) = 1 ( 1/t - 1)/(t-1) = 14 , where t ≠ 1 1/t - 1 = 14t - 14 times t 1 - t = 14t^2 - 14t 14t^2 - 13t - 1 = 0 (14t + 1)(t - 1) = 0 t = -1/14
*January 21, 2016*

**Calc**

why did you doubt it ?
*January 21, 2016*

**Calc**

f(2.01) = √9.03 f(2) = √9 avg rate of change = (√9.03 - √9)/(2.01-2) = .... I get .49958..
*January 21, 2016*

**math**

5cm --- 1 km 5 cm --- 1000 m 1 cm --- 200 m what is 250(1.2) ? what is 8(3.25)(4) ?
*January 21, 2016*

**math**

Study the reply I just made to Nina and see how critical brackets are. http://www.jiskha.com/display.cgi?id=1453394669 btw, your question factors nicely. Hint: If we want the denominator to cancel wouldn't we expect 2x-5 to be one of the factors of the top?
*January 21, 2016*

**math**

I assume you meant: (x^2 - x - 6)/(2x-6) and I assume you want it simplified. = (x-3)(x+2)/(2(x-3)) = (x+2)/2 , x ≠ 3
*January 21, 2016*

**Math**

f(1) = 7(1)^2 = 7 f(A) = 7A^2 avg rate of change = (7a^2 - 7)/(a-1) (7a^2 - 7)/(a-1) = 84 7a^2 - 7 = 84a - 84 7a^2 - 84a + 77 = 0 a^2 - 12a + 11 = 0 (a-11)(a-1) = 0 a = 11 or a = 1, but we have to reject a = 1 or else we would be dividing by zero A =11 check: f(11) = 7(121) = ...
*January 21, 2016*

**algebraic fractions**

The way you typed it ..... 8/4x-4 = 2x - 4 if you meant: 8/(4x-4) = 8/(4(x-1)) = 2/(x-1) , x≠1
*January 21, 2016*

**algebra**

her brother --- x Archie ------- x+12 four years from now: brother = x+4 Archie = x+12 + 4 = x+16 x+4 = (2/3)(x+16) solve for x and sub into original definitions
*January 21, 2016*

**College Calc**

find the time taken to go from A to B (220/55) hrs find the time from B to C add up the times divide (total distance/total time) editorial: This is College Calculus???
*January 21, 2016*

**algebra**

let the unit be be x then the tens digit is x+2 let the hundreds digit by y x + x+2 + y = 14 2x + y = 12 number: 100y + 10(x+2) + x = 100y + 11x + 20 number reversed: 100x + 10(x+2) + y = 110x + y + 20 but they are to be equal 100y + 11x + 20 = 110x + y + 20 99y = 99x y = x ...
*January 21, 2016*

**Math**

since g(x) = x, f(g(x)) = f(x) = sinx
*January 21, 2016*

**math**

for a 18 month period, the last term is 18 and the sum is 1+2+3+...+18 ( ----> sum(n) = n(n+1)/2) = 18(19)/2 = 171 Do the others the same way. I recall this rule as something we taught way back in the 60's Here is a challenge for you: Phone any bank, mortgage company, ...
*January 21, 2016*

**maths**

by definition term8 = a + 7d sub in our data 3 + 7d = 31 7d = 28 d = 4
*January 21, 2016*

**maths**

Area of trap = (1/2)(a+b)(h) where a and b are the two parallel sides and h is the height between them you have one missing unknown, just plug everything in, and solve
*January 21, 2016*

**algebra**

so she paid 3/4 of the original. solve (3/4)x = 42
*January 21, 2016*

**trigonometry**

You will need brackets to establish the proper order of operations. e.g , the way you have it, the cos^3 Ø would be divided by sinØ, but it probably is divided by (sinØ + cosØ) etc.
*January 21, 2016*

**trigonometry**

I just googled your question after fixing the typo, and found all kinds of results. Here is just one of them: http://www.algebra.com/algebra/homework/Trigonometry-basics/Trigonometry-basics.faq.question.703828.html let Google be your friend
*January 21, 2016*

**trigonometry**

tan 3Ø = tan (2Ø + Ø) = (tan 2Ø + tanØ)/(1 - tan 2Ø tanØ) and tan 2Ø = 2tanØ/(1 - tan^2 Ø) let x = tanØ for ease of typing then tan 3Ø = (tan 2Ø + x)/(1 - xtan 2Ø) = ( (2x/(1 - x^...
*January 21, 2016*

**math**

treat the 2 as one item, so you are arranging 5 which is 5! but the two students could be interchanged, so number of ways to seat the students = 2(5!) = ...
*January 21, 2016*

**Math**

If you want f(g(x)), then .. = f(3-x) = 2^(3-x)
*January 21, 2016*

**math**

Did you make a sketch? Shade in the area not reached by the horse The area reached by the horse is 1/4 of a circle with radius of 7 m that area = (1/4)π(49) = 12.25π m^2 Area of the whole square = 100 m^2 So .....
*January 21, 2016*

**math**

looks like the x was decreased by 5, and the y was bumped up by 8, so (x,y) ---> (x-5, y+8)
*January 20, 2016*

**math**

In the scale drawing, each side is 10 cm , (10^2 = 100) if 1 cm ---> 2 ft then 10 cm ---> 20 ft area of real floor = 20^2 ft^2 = 400 ft^2
*January 20, 2016*

**maths**

1. In your GP, a = 2, r = 2 sum(n) < 1500000 a(r^n - 1)/(r-1) > 1500000 2(2^n - 1)/(2-1) > 1500000 2^n - 1 > 750000 2^n > 750001 take log of both sides , and use log rules n log2 > log 750001 n > log 750001/log2 n > 19.5 at n = 19 we won't be there...
*January 20, 2016*

**Finance 101**

Time to get a more up-to-date textbook. 10% mortgage?? anyway... monthly rate = .10/12 = .008333... (store in your calculator) n for 5 years = 60 n for 30 years = 360 monthly payment at original rate -- P P(1 - 1.008333...)^-360)/.0083333 = 150000 P = 1316.36 amount if no ...
*January 20, 2016*

**Math**

The leg will be the hypotenuse of a right-angled triangle with base 2x and height 6 H^2 = 4x^2 + 36 H = √(4x^2 + 36) = 2√(x^2 + 9)
*January 20, 2016*

**Math**

David's marbles --- x Sam's marbles -----x After Sam lost his marbles: Sam --- x-50 David -- x+50 x+50 = 5(x-50) x+50 = 5x - 250 -4x = -300 x = 75 they had 75+75 or 150 marbles between them Your previous post contains the "same" question, just the numbers and...
*January 20, 2016*

**Math**

John --- x yrs Mary --- 2x yrs Bob --- 4x yrs in 22 years from now: John: x+22 Mary: 2x+22 bob: 4x+22 4x+22 = 2(x+22) 4x+22 = 2x + 44 2x=22 x=11 So Mary is now 22
*January 20, 2016*

**probability and statistics**

Since you state no restriction, I will assume that the plate can start with a 0 first let's select our plate: number of selections = C(2,2) C(4,3) = 4 then each of those can be arranged in 5! ways. number of possible arrangements = 4(5!) = 480
*January 20, 2016*

**Pre-Calc**

confirmation by Wolfram: http://www.wolframalpha.com/input/?i=simplify+sin%28arcsinx+%2B+arccosx%29
*January 19, 2016*

**Pre-Calc**

arcsinx is an angle Ø so that sinØ = x/1 = x arccosx is an angle Ø so that cosØ = x/1 thus sinØ = cosØ and Ø = 45° sin(arcsinx + arccosx) = sin(45° + 45°) = sin 90° = 1
*January 19, 2016*

**Pre-Calc**

secx(sinx/tanx) = (1/cosx)(sinx)(cosx/sinx) = 1
*January 19, 2016*

**algebra**

let Jimmy's rate be 1/x Jack's rate = 1/10 combined rate = 1/x + 1/10 = (x+10)/(10x) 1/( (x+10)/(10x) ) = 4.44 10x/(x+10) = 4.44 10x = 4.44x + 44.4 5.56x = 44.4 x = 7.9856 Jimmy alone would take 7.99 hrs or appr 8 hrs combined rate = 1/10 + 1/8 = 9/40 time at combined ...
*January 19, 2016*

**math-linear equations**

h + c = 340 h = c + 52 sub the second into the first: h + c = 340 c+52 + c = 340 2c = 288 c = 144 then h = 144+52 = 196 So 144 cows and 196 horses
*January 19, 2016*

**Math**

Did not check if the ordered pairs satisfy, but 6x + 10y ≥ 120 is the only correct inequality.
*January 19, 2016*

**Math**

2 years ago you were x 2 years ago your mom was 4x 18 years from now, you will be x+20 18 years from now, your mom will be 4x+20 x+20 = (1/2)(4x+20) x+20 = 2x + 10 10 = x 2 years ago, you were 10, your mom was 40 you are now 12, your mom is now 42 check: 2 years ago you were ...
*January 19, 2016*

**math**

the number should look like this (x+1)x9 "Those two numbers equal 11" Did you mean that their sum is 11? I will assume thus. x+1 + x = 11 x = 5 your number is 659
*January 19, 2016*

**math help**

let y = 2x^4 - 3x^2 - 7x + 1 y ' = 8x^3 - 6x - 7 newx = x - y/y' = x - (2x^4 - 3x^2 - 7x + 1)/(8x^3 - 6x - 7) =(6x^4- 3x^2 - 1)/(8x^3 - 6x - 7) x = 1.75 newx = 1.8162 ---> x newx = 1.8111 ---> x newx = 1.811102 I would call 1.8111 a good estimate
*January 19, 2016*

**Maths**

a+6d=11 a+(n-1)d=3 subtract them: 6d - (n-1)d = 8 6d - nd + d = 8 7d - nd = 8 d = 8/(7-n) , it should be noted that n ≠ 7 back in the 1st: a + 48/(7-n) = 11 a = 11 - 48/(7-n) = (77 - 11n - 48)/(7-n) = (29 - 11n)/(7-n) so the terms are: (29 - 11n)/(7-n) , (37 - 11n)/(7-n...
*January 19, 2016*

**math**

tan^2 x = 3 tan x = ±√3 we know tan 60° = √3 so x = 60° , 120° , 240° or 300° or in radians x = π/3, 2π/3, 4π/3, or 5π/3
*January 19, 2016*