Tuesday

September 27, 2016
Total # Posts: 36,030

**MAth**

24m^9 - 27m^7 - 24m^5 = 3m^5(8m^4 - 9m^2 - 8) so the GCF is 3m^5

*July 12, 2016*

**Maths**

your equations are jumbled and garbled did you mean: -7x + 7y = -21 and -9x + 9y = -27 ?? dividing the first one by -7 and the second by -9 produces the same equation, x - y = 3 So they are both one and the same equation. Look up how each of your classifications is defined in ...

*July 12, 2016*

**pre algebra**

prob(red) = 1/3 prob(not red) = 2/3 odds in favour of red = (1/3) : (2/3) = 1 : 2

*July 12, 2016*

**math**

Assuming a total loss, what is 80% of 288,000

*July 12, 2016*

**Math**

There are 69 shells, you said so.

*July 12, 2016*

**Algebra**

I agree with PsyDAG Your question makes about as much sense as this one: Sara can drive to Chicago in 5 hours, Jasmin can do the same trip in 7 hours. How long will it take the two of them driving together?

*July 12, 2016*

**pre cal**

x^4>4x^2 x^4 - 4x^2 > 0 x^2(x^2 - 4) > 0 x^2(x+2)(x-2) > 0 critical values are -2, 0, +2 for x < -2 , --->(+)(-)(-) >0 , so true for x = 0 , no good for -2 < x <0 , say x = -1 ---> (+)(+)(-) < 0 , false for 0 < x < 2 , ---> (+)(+)(-) &...

*July 12, 2016*

**Calculate y' and y'' at the point (1,1)**

Gee, you posted this same question only 3 minutes ago. I know we are fast but .... btw, it has been answered.

*July 12, 2016*

**Math**

first derivative: 5x y^2 + 9y - 14 = 0 5x(2y)dy/dx + 5y^2 + 9dy/dx = 0 dy/dx(10xy + 9) = -5y^2 dy/dx = -5y^2/(10xy+9) at (1,1) dy/dx = y' = -5/19 , you had that from 5x(2y)dy/dx + 5y^2 + 9dy/dx = 0 10xy y' + 5y^2 + 9 y' = 0 recall the rule for derivatives of triple...

*July 12, 2016*

**pre cal**

Just noticed that Steve answered your question yesterday. http://www.jiskha.com/display.cgi?id=1468295145 Why are you repeating it? (this time with a typo)

*July 12, 2016*

**pre cal**

First of all, your equation contains a typo, it should say: h(t)= (−g/2) t^2+v0t+h0 secondly, what units are you using? thirdly, did you drop the rock or did you give it a downwards velocity? let me know before I can answer your question.

*July 12, 2016*

**Math - Studying for Pre Calc exam!**

6 sin 2x − 8 cos x + 9 sin x = 6 12sinxcosx - 8cosx + 9sinx - 6 = 0 4cosx(3sinx - 2) + 3(3sinx - 2) = 0 (3sinx - 2)(4cosx + 3) = 0 sinx = 2/3 OR cosx = -3/4, the last one is not possible sinx = 2/3 x = .7297.. which matches b) Make sure your calculator is set to radians ...

*July 12, 2016*

**math**

Haven't done this kind of question in over 55 years, had to look it up try this: http://math.stackexchange.com/questions/315317/orthogonal-trajectories-for-a-given-family-of-curves

*July 12, 2016*

**Math**

don't like fractions, so how about Ø = x/2 or x = 2Ø then your equation becomes cosØ - sin 2Ø = 0 cosØ - 2sinØcosØ = 0 cosØ(1 - 2sinØ) = 0 cosØ = 0 or sinØ = 1/2 Ø = π/2, 3π/2...

*July 12, 2016*

**Pre-Cal**

tan^(2)xsecx+secx = secx( tan^2 x + 1) , common factor = secx(sec^2 x), by identity = sec^3 x (csct-sint)/(csct) = (1/sint - sint)/(1/sint) multiply top and bottom by sint = (1 - sin^2 t)/1 = cos^2 t

*July 11, 2016*

**Pre-Cal:(Cont.)**

2 cos 2θ − 1 = 0 cos 2Ø = 1/2 I know cos π/3 = 1/2 , and the cosine is positive in I and IV so 2Ø = π/3 , in I OR 2Ø = 2π - π/3 = 5π/3 , in IV Ø = π/6 or Ø = 5π/6 (Ø = 30° or Ø...

*July 11, 2016*

**Math**

I am sure you meant: f(x) = (ax + b)/(cx + d) "the horizontal asymptote is y=2" ----> ax/(cx) = 2 , as x ---> infinity a/c = 2 a = 2c so we have f(x) = (2cx + b)/(cx + d) "the vertical asymptote is x =5" ---> (x-5) <---> cx + d c = 1, d = -5 ...

*July 11, 2016*

**Even or Odd Funciton**

let's take your answer a bit further ... 1/((-x)^3-5(-x)) = 1/( -(x)^3 + 5x) = -1/(x^3 - 5x) = - f(x) so the function is odd by definition: odd ---> f(-x) = -f(x) even ---> f(-x) = f(x)

*July 11, 2016*

**calculus**

You are correct!

*July 11, 2016*

**calculus**

I assume you used: tan(A - B) = (tanA - tanB)/( 1 + tanAtanB) then (tan17pi/12 - tan pi/4) / (1+tan 17pi/12 tan pi/4) = tan(17π/12 - π/4) = tan( 7π/6) or tan 210° ---> quad III = 1/√3

*July 11, 2016*

**math**

I am sure you meant: (tan 7x − tan x)/( 1 + tan 7x tan x) compare to : tan(A-B) = (tanA - tanB)/(1 + tanAtanB)

*July 11, 2016*

**math**

you should recognize this as the use of cos(A+B) cos 60° cos 65° − sin 60° sin 65° = cos(60°+65°) = cos 125°

*July 11, 2016*

**calculus**

poor choices for answers, they should have rationalized the answer. That's where my hint about a calculator comes in. Both our answers were (1/4)(√2 - √6) if you work that out on your calculator you get appr -.2588 working out c) you get appr -.2588 so c) is ...

*July 11, 2016*

**calculus**

correct Why not just check your result with a calculator?

*July 11, 2016*

**calculus**

60.1 − 43.9 cos πt/ 6 ≥ 77 − 43.9 cos πt/ 6 ≥ 16.9 cos πt/6 ≤ - .38496... consider cos πt/6 = - .38496... I know cos 1.1756.. = +.38496 so πt/6 = π - 1.1756 = appr 1.966 t = 3.755 or πt/6 = π + 1.1756.. = 4....

*July 11, 2016*

**amth**

I know cos 30° or cos π/6 = +√3/2 so x/2 = 180-30 or x/2 = 180+30 x = 300° or x = 420° or x = 5π/3 or 7π/3 To do these type of questions, you MUST know the ratio of sides of the 30-60-90° as well as the 45-45-90° triangles, and you MUST...

*July 11, 2016*

**math**

incomplete question. Are you not getting any interest on your money?? in that case amount = 450 + 58.5w

*July 11, 2016*

**math**

Along the 12 ft length, the 6 inch tiles will fit exactly and you will need 24 along that side. Along the 14 ft side, you will need 28 tiles. total = 24(28) or 672 tiles or area = 168 square feet, but with 6 inch tiles, you will need 4 tiles per square inch total = 4(168) = ...

*July 11, 2016*

**Math**

and here is why ... pq - q = p+12 q(p - 1) = (p+12) q = (p+12)/(p-1) = 1 + 13/(p-1) clearly p > 1 , to have positive values for q to be an integer, 13/(p-1) has to be an integer, that is, p has to be either 2 or 14 so (2,14) or (14,2) e.g. if p = 2, q = 14 , Steve's ...

*July 11, 2016*

**pre cal**

I think you have a typo. Being familiar with these type of questions, it probably said: (x/x-1)^2 - (x/x+1) -2=0 if so, let y = x/(x-1) and carry on like I showed you in your previous post

*July 11, 2016*

**pre cal**

hint: let y = x^2, then your equation becomes 2y^2 - 5y + 2 = 0 carry on

*July 11, 2016*

**mathematics**

total = 36 students prob(boy) = 15/36 = 5/12

*July 11, 2016*

**Pre Calculus**

sum of sines: sinA + sinB = 2sin( (A+B)/2) cos( (A-B)/2) then: sin 150° + sin 30° = 2sin 90° cos 60° = 2(1)(1/2) = 1 Difference of sines: sinA - sinB = 2cos( (A+B)/2) sin( (A-B)/2) then: sin 4θ − sin 2θ = 2cos(3Ø)sin Ø

*July 11, 2016*

**pre cal**

let √x = y then: 2y^2 - 5y + 2 = 0 (2y -1)(y -2) = 0 y = 1/2 or y = 2 √x = 1/2 ----> x = 1/4 or √x = 2 ------> x = 4 or 2x+2 = 5√x square both sides: 4x^2 + 8x + 4 = 25x 4x^2 - 17x + 4 = 0 (x - 4)(4x - 1) =0 x = 4 or x = 1/4 btw, in both solutions...

*July 11, 2016*

**Pre-Calculus 11**

-3* cube root of 2 is a negative number, so your result has to stay negative. change it to - cuberoot(54)

*July 10, 2016*

**math**

just use for formulas for an AS term(n) = a + (n-1)d for yours a=22000 d=500 n=7 sum(n) = (n/2)(first + last) (you have the last term from above) or sum(n) = (n/2)(2a + (n-1)d )

*July 10, 2016*

**Math**

number of men --- m number of girls --- g m+g = 120 Tina danced with 7 men Reena danced with 8 men .... Raveena danced with 120-g men this is an arithmetic sequence with a=7, d=1 term(g) = m a + (g-1)d = m 7 + g-1 = m g - m = -6 also g+m = 120 add them 2g = 114 g = 57 m = 120-...

*July 10, 2016*

**Math**

construct your right-angled triangle. r^2 = x^2 + y^2 , (x is a side , not an angle) 2^2 = x^2 + 1^2 , since sinØ = opposite/hypoenuse or y/r x^2 = 3 x = √3 , we know the angle must be in Quad I sinx = 1/2 --- given cscx = 2 cosx = √3/2 secx = 2/√3 ...

*July 10, 2016*

**Pre Calculus**

5.4 radians coterminal with 5.4 - 2π = -.883.. radians, which is in the IV th or if you want to "think" in degrees 1 rad = 180/π ° 5.4 rad = 309.39.. ° ----> 4th

*July 10, 2016*

**Pre Calculus**

I did this yesterday http://www.jiskha.com/display.cgi?id=1468085862

*July 10, 2016*

**mathematics**

of the 40 oranges, 12 are unripe ----> 28 are ripe prob(ripe) = 28/40 = 7/10 so prob(unripe) = 1 - 7/10 = 3/10 you are correct

*July 10, 2016*

**maths**

nope , (x+y)^2=x^2+2xy+y^2

*July 10, 2016*

**math**

all the numbers that don't have a 5 in them: 8 x 9 = 72 , (they can start with 1,2,3,4,6,7,8,9 and they can end with 0,1,2,3,4,6,7,8,9 ) Those with a 5 are 100-72 = 28 prob(have a 5) = 28/100 = 7/25

*July 10, 2016*

**math**

smallest --- x middle one -- 2x largest ------ 3x x + 2x + 3x = 180 solve for x, sub back into my definitions

*July 10, 2016*

**Pre-calculus**

x = a(y-3)^2 + 0 but (4,9) lies on it, so 4 = a(9-3)^2 + 0 4 = 36a a = 1/9 x = (1/9)(y-3)^2 is your equation.

*July 10, 2016*

**Pre-Calculus 11**

is it (5/7)√(3/2) ? or 5/(7√(3/2) )?

*July 9, 2016*

**math**

3x-5y=16 -9x+15=48 notice that if you divide the 2nd by -3 , you get 3x - 5y = -16 clearly you will have two different parallel lines, thus no solution. or if we subtract: 3x-5y=16 3x-5y=-16 0 = 32 not very likely !!!! , so no solution

*July 9, 2016*

**Mathematics**

Memorize this relationship until you can state it in your sleep. π radians = 180° Use it to answer this, and your two previous questions.

*July 9, 2016*

**Mathematics**

repeatedly add 360° and note the results

*July 9, 2016*

**Pre Calculus**

You really really really MUST know that.

*July 9, 2016*

**Mathematics**

What is (2π - 11π/13) ? I get 15π/13 , which is not one of your choices. Do you have a typo?

*July 9, 2016*

**Pre Calculus**

same type of question as your last one

*July 9, 2016*

**Pre Calculus**

8π / 7= π + (1/7)π so just a bit more than π, so in quadrant III here is a "sneaky way" set your calculator to radians take sin 8π/7 to get a negative take cos 8π/7 to get a negative the only quadrant in which both sine and cosine are ...

*July 9, 2016*

**Maths**

Everybody studying trig should know the ratio of sides, and thus the trig ratios, of the 30-60-90° right angled triangles, as well as the 45 -45-90° triangle for the 30-60-90 the sides are 1 - √3 - 2 units respectively looking at your sketch of that triangle, ...

*July 9, 2016*

**Spherical Trigonometry**

h/100 = tan 38° solve for h

*July 9, 2016*

**Calc.**

I assume we are looking at vectors, then (6,2y) - (5x,10) = (6,-4) 6-5x = 6 , solve for x 2y - 10 = -4, solve for y

*July 8, 2016*

**Calc.**

⃗⃗u dot ⃗v =| ⃗⃗u| | ⃗v| cosØ, where Ø is the angle between them 2 + 20 + 2 = √21 √30 cosØ 24/(√630 =cosØ I get Ø = appr 17.02° check my arithmetic

*July 8, 2016*

**Pre-Cal**

I will do the 2nd one, which is the harder of the two. Follow my steps to do the first one. sinx = -5/13 ,and the angle x is in III recall that sinØ = y/r so y = -5, r = 13 sketch a right-angled triangle in III with hypotenuse 13 and y = -5 x^2 + y^2 = r^2 x^2 + 25 =169...

*July 7, 2016*

**Raquel, check your answer - Algebra**

Racquel, check your calculations. 2000(.08) + 8000(.09) = 880 , not 860 as needed.

*July 7, 2016*

**Algebra**

sue's rate = 1/60 (driveways/minute) Tom's rate = 1/35 (driveways/minute) combined rate = 1/60+1/35 = 19/420 (driveways/minute) time at combined rate = driveway/( (19/420) (driveways/minute) ) = 420/19 minutes = 22.1 minutes

*July 7, 2016*

**pre cal**

well, why don't you try expanding (x+s)^2 to see what comes out. btw, we use ^ to show exponents eg. x^2 is "x squared"

*July 6, 2016*

**Math**

Just translate the English using your definitions of a GS ar^3 = 30 ar^8 = 960 divide the 2nd by third, the a's will cancel r^5 = 32 r = 2 in ar^3 = 30 a(8) = 30 a = 15/4

*July 6, 2016*

**pre cal**

I will assume you meant: x^2/162 +x/18 + 1/9 = 0 the LCD is 162, so multiply each term by that x^2 + 9x + 18 = 0 (x+3)(x+6) = 0 x = -3 or x = -6

*July 6, 2016*

**pre cal**

number of twenties --- x number of tens ------- 3x 20x + 10(3x) = 1950 50x =1950 x = 39 so there are 39 twenties and 117 tens check: 39(20) + 117(10) = 1950

*July 6, 2016*

**Pre Calculus**

You really need help pushing buttons on your calculator???

*July 6, 2016*

**Pre Calculus**

form the half-life equation, amount = 69(1/2)^(t/12.4) , where t is in years plug in 75 for t show me your work and I will help you with the others.

*July 6, 2016*

**lagdamat**

What is "lagdamat" ?? width ----- x length ----- 2x+2 x(2x+2) = 24 2x^2 + 2x - 24 = - x^2 + x - 12 = 0 I will leave it up to you to solve this very simple quadratic. Hint1, it factors Hint2, reject the negative

*July 6, 2016*

**math**

What is (3/10)(2/7)(2905) ?

*July 6, 2016*

**probability**

I read that as a binomial distribution. so C(4,1) (1/2)^1 (1/2)^3 = 4(1/2)^4 = 1/4 or there are 2^4 or 16 cases your event could be HTTT THTT TTHT TTTH, or 4 possibilities prob(exactly one head) = 4/16 = 1/4

*July 6, 2016*

**Analytic geometry**

Name your points A(-8,8) and B(-2,2) So you want PA = 2PB Use you distance between points formula: √( (x+8)^2 + (y-8)^2 ) = 2√( (x+2)^2 + y-2)^2 ) square both sides (x+8)^2 + (y-8)^2 = 4( (x+2)^2 + y-2)^2 ) I will leave it up to you to expand and simplify the equation

*July 6, 2016*

**math**

Ahh, I see you fixed the problem from your earlier post. a) 20 men, 12 women, choose 5, with exactly 3 men = C(20,3) x C(12,2) = 2053(66) = 135498 b) at least 4 women ---> 4 women or 5 women = C(20,1) x C(12,4) + C(20,0) x C(12,5) = 20(495) + 1(792) = 10692 check my arithmetic

*July 6, 2016*

**Math**

Since the room is square, its side is √350 = 5√14 m your carpet is only 5√14 by 3√14 So clearly you will need an extra 2√14 m

*July 6, 2016*

**math**

your wording is gibberish. How can you have a committee of 5 people "if exactly three men must be on each committee and at least four women on each committee" Are there two different questions here?

*July 5, 2016*

**Prealgebra**

correct about the conversion to start. 3 m = 300 cm 2 m = 200 cm, (isn't the metric system great??) but 300/10.5 = 28.5 , so you will need 29 one way, and 200/10.5 = 19.04.. darn!, you will have to have 20 along the width So you will need 20x29 or 580 tiles. ( in reality ...

*July 5, 2016*

**math**

Area of ellipse = abπ where a and b are 1/2 of the axes respectively, that is, a = 7, b = 5

*July 5, 2016*

**Pre Calculus**

so you want: y = log3 (127) or 3^y = 1/27 , by definition of logs 3^y = 3^-3 y = -3 f(1/27) = -3

*July 5, 2016*

**Pre Calculus**

recall that ln 1 = 0 so x-3 = 1 x = 4

*July 5, 2016*

**Pre Calculus**

Where does the b come from in all your answers? Where does the 19 come from in all the answers? I suspect a typo

*July 5, 2016*

**Math of investigation**

Same post answered by Steve http://www.jiskha.com/display.cgi?id=1467634318

*July 4, 2016*

**Pre-Calculus 11**

∛5*5*5*3/4 = 5∛3/4 , assuming the 4 is not part of the cube root

*July 4, 2016*

**Pre Calculus**

I will try to show my synthetic division, the .... are spaces: 6+√6 | 1 ........ -11 ........ 18 ........ 32 .................... 6+√6 .... √6-24 .... -30 ............ 1 ..... √6-5 ..... √6-6 ........ 2 showing that: x^3-11x^2+18x+32 = (x-6-√...

*July 4, 2016*

**maths**

the time taken would be inversely proportional to the number of men, that is , the men we have working the less time it takes. t = k/m k = tm given: 8 men take 6 months k = 6x8 = 48 when m = 12 t = 48/12 = 4 or number of "man-months" = 48 time for 12 men = 48/12 = 4 ...

*July 4, 2016*

**MATH**

area of whole flag = 9000 cm^2 width of thin stripe --- x width of thicker stripe --- 2x area of stripes = 2x(90) + x(100) - 2x^2 ( we have to subtract the intersection of the stripes or else we would count it twice) = 280x - 2x^2 4500 = 280x - 2x^2 2x^2 - 280x + 4500 = 0 x^2...

*July 4, 2016*

**math**

You know how to find the area of a square if you know the sides, right? area = (5x+3y)^2 m^2 = (25x^2 + 30xy + 9y^2) m^2

*July 4, 2016*

**math**

which digits? at the left of what? at the right of what?

*July 4, 2016*

**maths**

unit digit --- x tens digit --- x+7 10(x+7) + x = 10(x + x+7) 10x + 70 = 20x + 70 10x = 0 x = 0 so the number is 70

*July 4, 2016*

**maths**

unit digit --- x tens digit -- 4x the number is 10(4x) + x or 41x the number reversed is 10x + 4x or 14x 41x - 14x = 54 27x = 54 x = 2 the original number is 82 check: 82-28 = 54 , all is good.

*July 4, 2016*

**math**

original number ---- x/(x+7) new number: (x+17)/(x+7-6) = (x+17)/(x+1) (x+17)/(x+1) = 2 2x + 2 = x+17 x = 15 the original number was 15/22

*July 4, 2016*

**math**

There are billions and billions of those. Some of them are: 3 and 5 6 and 10 30 and 50 5.4 and 9 6√3 and 10√3 -9 and -15 .... etc

*July 4, 2016*

**Math**

amount of original money ---- x (1/5)x + (1/4)(4/5)x + 360 = x x/5 + x/5 + 360 = x times 5, the LCD x + x + 1800 = 5x 3x = 1800 x = 600 check: he spent 1/5 of 600, or 120 , leaving him with 480 he spend 1/4 of 480 on food, leaving him with 360

*July 4, 2016*

**Maths**

V = (4/3)π r^3 dV/dt = 4π r^2 dr/dt when V = 2000 (4/3)πr^3 = 2000 r^3 = 1500/π r = (1500/π)^(1/3) = 7.8159... I stored in my calculator's memory so in dV/dt = 4π r^2 dr/dt 125 = 4π (7.8159...)^2 dr/dt dr/dt = .1628618 rate of change of ...

*July 3, 2016*

**MATH**

The hexagon is made up 6 equilateral triangles with sides of 9 ft Area of one of them = (1/2)(9)(9)sin60° = (81/2)(√3/2) = 81√3/4 area of whole hexagon = 6(81√3/4) = 243√3/2 area of whole hexagonal prism = 2(243√3/2) + 6(9)(6) = (243√3...

*July 3, 2016*

**math**

find the slope, then use the steps I showed you in your first post

*July 3, 2016*

**math**

Since your new line is parallel to the given line, it will differ only in the constant, so it will be -7x + 6y = c plug in the given point: -7(-1) + 6(-4) = c c = -17 new equation: -7x + 6y = -17 or 6y = 7x - 17 y = (7/6)x - 17/6

*July 3, 2016*

**math**

from what I had: y+6 = 8x + 40 y = 8x + 34 ---> this is correct standard form: 8x - y = -34 ---> this is correct general form: 8x - y + 34 = 0 ---> this is correct

*July 3, 2016*

**math**

y+6 = 8(x+5) I will leave it up to you to change it to the required form.

*July 3, 2016*

**Math**

let the amount of money be m let the number of people sharing be x let each persons share be y then xy = m second case: number of people = x+8 share of each person = y-1 then m = (x+8)(y-1) = xy + 8y - x - 8 thus: xy+8y-x-8 = xy x = 8y - 8 , where y > 0 , and y is a natural...

*July 3, 2016*

**Math**

If the new line is to be parallel to y = 4x +1, it will differ only in the constant, so let it be y = 4x + b, plug in the given point, find b, and you are done

*July 3, 2016*

**math**

bend = k mass given: 10 cm = k 4 kg k = 10/4 cm/kg or (5/2) cm/kg if mass = 7kg bend = (5/2)(7) = 17.5 cm

*July 3, 2016*

**maths**

let the total number be x (4/5)x are boys (1/5)x are girls, but (1/5)x = 100 x = 500 So we have 100 girls and 400 boys

*July 3, 2016*