Friday

April 29, 2016
Total # Posts: 34,377

**math**

I don't understand. We don't use "texting" here. Proper English still has its place.
*January 27, 2016*

**maths number system**

I am not familiar with "lub"s and "glb"s.
*January 27, 2016*

**Mathematics**

I will assume your middle term is 24x^3 9x^4 - 24x^3 + 16x^2 = 0 x^2( 9x^2 - 24x + 16) = 0 mmmhh, the first and last terms are perfect squares, could it be ... ??? sure enough: x^2(3x - 4)^2 = 0 x = 0 , x = ±2/√3
*January 27, 2016*

**math**

how about just ..... 500x + 80000 = 25000 500x = 170000 x = 340
*January 27, 2016*

**álgebra**

least perimeter when your rectangle is a square. so each side is √32 etc.
*January 27, 2016*

**calculus**

confirm if the equation is as you typed it or if c(t) = .2t/(t^2 + 1)
*January 27, 2016*

**math**

so you have 2x + 2y = 180 x+y = 90 if x = 40, y = 50 your angles are 40, 40, 50, 50
*January 27, 2016*

**math**

granola : raisins = 2:3 = 2x : 3x if 3x = 24 x = 8 then granola = 2x = 16
*January 26, 2016*

**math**

almonds : walnuts : pecans = 4x : 3x : 8x if 8x = 40 x = 5 walnuts = 3x = 15
*January 26, 2016*

**maths**

Arithmetic series with a = 19 d = -4/5 a + (n-1)d < 0 19 + (n-1)(-4/5) < 0 19 - (4/5)n + 4/5 < 0 times 5 95 - 4n + 4 < 0 -4n < -99 n > 99/4 n > 24.75 so it must be term(25) which is the first one negative. check: term(25) = 19 + 24(-4/5) = -1/5 term(24) = ...
*January 26, 2016*

**Math**

Since the angle is 45° , the triangle is an isosceles right-angled triangle. no work needed, the distance = 5300 ft
*January 26, 2016*

**Algebra**

Just translate into math larger --- x smaller --- y x-y = 16 5y = 2x - 8 from the first: y = x-16 5(x-16) = 2x - 8 5x - 80 = 2x - 8 3x = 72 x = 24 , then y = 8 the larger is 24, the smaller is 8 check: difference is 24-8 = 16 , check! five times the smaller = 40 twice the ...
*January 26, 2016*

**math**

My reasoning is like this: Number of pair for each rank = C(4,2) = 6 so all possible pairs of the same rank = 13(6) = 78 possible pairs = C(52,2) = 1326 prob(pair of the same rank) = 78/1326 = 1/17
*January 26, 2016*

**illogical data - Science**

Your data makes no sense! How can he "run" almost 200 km in about 3 hours??? Fix your question before so it can be answered realistically.
*January 26, 2016*

**math**

looks like we already have a common denominator of 3 2a/3 + a/3 = 3a/3 = a
*January 26, 2016*

**mathematics**

you posted the same question three times at 1 minute intervals. I know we are fast, but really ...? look back to earlier post
*January 26, 2016*

**mathematics**

done, look back to your previous post of this
*January 26, 2016*

**mathematics**

The four numbers would be a, ar, ar^2, and ar^3 a(ar^3) = 243 (a^2)(r^3) = 243 or ar(ar^2) = 243 ar + ar^2 = 36 ar(1 + r) = 36 divide ar(ar^2) = 243 by ar(1+r)=36 ar^2/(1+r) = 27/4 4ar^2 = 27 + 27r a = (27+27r)/(4r^2) = 27(1+r)/(4r^2) plug into: a^2 r^3 = 243 [ 27(1+r)/(4r^2...
*January 26, 2016*

**Math**

arrhhhhgggg! (a+x)^2/3+(a-x)^2/3=3(a^2-x^2)^1/3 (a+x)^2/3+(a-x)^2/3=3( (a+x)(a-x) )^1/3 divide both sides by (a-x)^(2/3) (a+x)^(2/3) / (a-x)^(2/3) + 1 =3( (a+x)(a-x) )^1/3 /(a-x)^(2/3) ((a+x)/(a-x))^(2/3) + 1 = 3 (a+x)^(1/3) / (a-x)^(1/3) ((a+x)/(a-x))^(2/3) + 1 = 3 ((a+x)/(a-...
*January 26, 2016*

**math**

just translate to Math let the smaller be x let the larger by y clearly : x+y 120 "that thrice the smaller one is equal to twice the larger one" ---> 3x = 2y from the first: y = 120-x into the 2nd: 3x = 2(120-x) 3x = 240 - 2x 5x = 240 x = 48 smaller is 48, the ...
*January 26, 2016*

**Math (Please help)**

no, I found the average radius r I was hoping you would be able to find its volume. V = (4/3)π r^3 , (I used it)
*January 26, 2016*

**Math (Please help)**

Change in volume = (28)(18)(5) cm^3 = 2520 cm^3 This was caused by the 12 marbles that volume was 12(4/3)πr^3 = 16πr^3 16πr^3 = 2520 r^3 = 2520/(16π) r = (2520/(16π))^(1/3) I got appr 1.69 cm check my arithmetic
*January 26, 2016*

**math**

make a sketch let the original square be 4x by 4x, (avoiding fractions) after 1 fold: 4x by 2x after 2 folds: 4x by x perimeter = 2(4x+x) = 20 5x = 10 x = 2 original square was 8 by 8 and original perimeter was 4(8) = 32
*January 26, 2016*

**math**

We have to find how high the water level is (20)(15)(h) = 4800 h = 16 So we have the base: 20(15) = 300 and the four sides: 2(20)(16) + 2(15)(16) = 1120 Surface area of the problem = 1420 m^2 check my arithmetic
*January 26, 2016*

**MATH**

a reflection in the x-axis can be written as r1: (x,y) ---> (x, -y) so: A(2,1) ---> A1(2,-1) B(4,3) ---> B2(4,-3) C(3,5) ---> C3(3,-5) r2: (x,y) --->(5-x+5,y) = (10-x,y) A2(2,-1) ---> A3(8,-1) B2(4,-3) ---> B3(6,-3) C2(3,-5) ---> C3(7,-5) suppose we do ...
*January 26, 2016*

**maths**

Did you mean a 2.8 kilolitre tank? I have not idea what a 2.8 km tank is.
*January 25, 2016*

**5 QUESTIONS PLZ HELP!**

1. by definition, 20% = 20/100 = 1/5 2. so it the same way 3. same thing 4. 14% = .14 1/8 = .125 , which is < .14 5. Why not change the all to decimals, then it is easier to see 7/14 = .5 .25 = .25 2/5 = .4 32% = .32 now order the decimals
*January 25, 2016*

**math**

just add them in pairs and see which comes closest to 1 without going under. Remember 5/6 is almost 1 , so that should give you a hint
*January 25, 2016*

**math**

Wouldn't you be a bit suspicious that perhaps 2x-5 factors into the top? why not try it. (2x-5)(.......) = 6x^2 - 11x - 10 You should be able to figure out the second factor without actually dividing.
*January 25, 2016*

**math**

I will assume you meant: (x^2 - x - 6)/(2x-6) , those brackets are needed = (x-3)(x+2)/(2(x-3)) = (x+2)/2 , x ≠ 3
*January 25, 2016*

**College Algrebra**

let the time it took be t seconds they ran the same time speed of faster runner = .25/60 mi/s =1/240 mi/s speed of slower runner = .25/66 mi/s = 1/264 mi/s (1/240)t + (1/264)t = 1/4 (7/880)t = 1/4 t = (1/4)(880/7) = 220/7 seconds or appr 31.43 seconds
*January 25, 2016*

**trigonometry**

I will assume you made a sketch. On mine, I let the top of the house across the street be P and its bottom Q. I let the point directly across the window (W) be R We know QR = 20 tan15° = 20/WR WR = 20/tan15 In the other triangle, tan5° = PR/WR PR = WRtan5 = (20/tan15)(...
*January 25, 2016*

**Math**

Didn't you state the dimensions of the second container ??
*January 25, 2016*

**Calc help!**

probably meant: x/(x-3) + (x+1)/(x+3) and then Damon's steps take over
*January 25, 2016*

**Maths**

Testices ??? lol AB and BC would be chords in your circle and the centre would be the intersection of the right-bisectors. One of them: slope AB = (1/3) so slope of perpendicular = -3 midpoint of AB = (7/2 , 7/2) equation: y - 7/2 = -3(x - 7/2) y - 7/2 = -3x + 21/2 3x + y = 14...
*January 25, 2016*

**Math**

since 45/6 = 7 1/2, he has only enough carnations to make 7 bouquets. He has more than enough roses for those 7 bouquets.
*January 25, 2016*

**Math**

P and Q are the intersection points of x-y+1 = 0 and the circle x^2 + y^2 = 25 sub y = x+1 into the circle x^2 + (x+1)^2 = 25 x^2 + x^2 + 2x + 1 - 25 = 0 x^2 + x - 12 = 0 (x+4)(x-3) = 0 x = 3 or x = -4 y = 4 or y = -3 so P(3,4) and Q(-4,3) are our two points Height of triange...
*January 25, 2016*

**math**

you want the sum of 0/4^0 + 1/4^1 + 2/4^2 + 3/4^3 + ... = 0 + 1/4 + 2/16 + 3/64 .. sum(0) = 0 sum(1) = 0+1/4 = 1/4 sum(2) = 1/4 + 2/16 = 6/16 sum(3) = 3/8 + 3/64 = 27/64 sum(4) = 27/64 + 4/256 = 112/256 .. looks like the denominators follow the pattern sum(n) = ??/4^n so how ...
*January 25, 2016*

**math**

speed = distance/time apply to your 3 cases.
*January 25, 2016*

**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*