Wednesday

January 28, 2015

January 28, 2015

Total # Posts: 28,765

**math**

If I understand correctly there would have been 4 transactions. let the amount that each child has originally be x first transaction: 1st child -- x-9 each of remaining 9 children has x+1 2nd transaction: 1st child -- x-9 2nd child -- x+1 - 8 = x-7 each of remaining 8 children...
*November 17, 2014*

**proportion test**

new machine, defect rate is 85/820 = .1037 or 1037% draw you conclusion from that
*November 16, 2014*

**Math**

The question was to "find all possible roots" so you would try f(1), f(-1) , f(2) ...., f(±12) so you must try all of these unfortunately, none are equal to zero, so you have no rational roots.
*November 16, 2014*

**Math**

It is a 4th degree equation, so at most you could have 4 roots How can you possible get 6 of them ?
*November 16, 2014*

**math**

√(31-9x) = 5 - x square both sides 31 - 9x = 25 - 10x + x^2 x^2 - x - 6 = 0 (x-3)(x+2) = 0 x = 3 or x = -2 BUT, since we squared, we must verify ALL answers if x = 3 LS = 3 + √4 = 5 RS = 5, YEahh if x = -2 LS = -2 + √49 = -2 + 7 = 5 = RS, YEAHH x = -2 or x = 3
*November 16, 2014*

**MATH 101**

using the difference of cubes factoring x^2 - 8 = 0 (x-2)(x^2 + 2x + 4) = 0 x = 2 or x = (-2 ±√-12)/2 = (-1 ± 2√3 i )/2 = -1 ± √3 i for 3 solutions, one real, two complex
*November 16, 2014*

**MATH 101**

not enough information. is f(x) linear ? we must assume that, since you only have 2 points, namely, (3,0) and (-4,0) slope = 0/-7 = 0 so we have a horizontal line and f(x) = 0 f(x) is the x-axis
*November 16, 2014*

**math**

let's look at x^2 + 2x + 4 = 0 by completing the square, (in this case the easiest way to solve it) x^2 + 2x = -4 x^2 + 2x + 1 = -4+1 (x+1)^2 = -3 but anything squared cannot be negative, so there is no real solution consider y = x^2 + 2x + 4 this parabola never touches or...
*November 16, 2014*

**Math**

let f(x) = 3x^3 + 2x^2-1 f(1) = 3 + 2 - 1 ≠ 0 f(-1) = -3 + 2 - 1 ≠ 0 f(1/3) = 1/9 + 2/9 - 1 ≠ 0 f(-1/3) ≠ 0 So there are no "nice" roots looking at the graph, there appears to be a real solution at appr x = 0.5 and two complex roots (the graph...
*November 16, 2014*

**CAL**

y = x^3/x- x would reduce to y = x^2 - x and (1,-2/3) would NOT lie on this curve. So there is something wrong with the way you typed it Use brackets to establish the correct form Otherwise this question is bogus.
*November 16, 2014*

**CAL**

could be the way you typed your equation. The way you typed it, why not just simplify x^3/x to x^2 ? That is why I am suspicious about the way it was typed. Did you mean y = x^(3/x) - x ?
*November 16, 2014*

**Derivative**

But, to even attempt this question, you MUST know the derivatives of the basic trig functions. in this case, use the quotient rule dy/dx = ( (1+sinx)(-sinx) - cosx(cosx) )/(1+sinx)^2 = (-sinx - sin^2 x - cos^2 x)/(1+sinx)^2 = (-sinx -1)(1+sinx)^2 = -(1+sinx)/(1+sinx)^2 = -1/(1...
*November 16, 2014*

**calculus**

#1, your dy/dt is correct b) correct, to the right when v(t) > 0 but they probably want to know when that happens look at your derivative, the denominator will always be positive, since it is something squared. So the ± of your v(t) is only determined by the ...
*November 16, 2014*

**Calculus Help**

It is not a matter of "choosing" here, you must calculate it. f ' (x) = cos(7-5x)(-5) = -5cos(7-5x) f '(π) = -5cos(7-5π) = 5cos(-8.7078..) = 3.770 Did you set your calculator to radians in your DRG mode ?
*November 16, 2014*

**Pre Albergra**

Just put on my tin-foil hat and got a message of 3.4 cm How did I do ?
*November 16, 2014*

**Calculus**

let x = √5 then x^2 - 5 let y = x^2 - 5 y' = 2x Newton said: newx = x - y/y' = x - (x^2 - 5)/(2x) = (2x^2 - x^2 + 5)/2x = (x^2 + 5)/(2x) x newx 3 2.3333.... 2.333... 2.23809... 2.23809... 2.23606... could have stopped here 2.23606.. 2.236067878 2.236067978.. 2....
*November 16, 2014*

**Trig**

The primary function is ln(...) we can only take logs of positive numbers now look at the sine curve only, and note where it lies above the x-axis so the intervals would be 0 < x < 90° or 360° < x < 450° or 720° < x < 810° or ... how about...
*November 16, 2014*

**Math**

first , because of the negatiave outer exponent = 1/(16x^2)^3/4 since (ab)^x = a^x * a^x we get 1/( (16^(3/4 ) * x^(3/2) now 16^(3/4) = (16^(1/4) )^3 = 2^3 = 8 so finally = 1/(8 (√x)^3 )
*November 16, 2014*

**math**

Volume of cylinder = π r^2 h you are given r and h, plug in the values and evaluate
*November 16, 2014*

**Elementary Math**

Ricardo --- x years Miriana ---- x+4 Ten years ago: Ricardo --- x-10 Miriam --- x+4 - 10 = x-6 x-6 = 3(x-10) easy to solve ... let me know what you get
*November 16, 2014*

**Math**

One would think that after trying this for two days, you might realize that you don't have enough information. e.g. If your tank is a large rectangular tank of 10 ft by 10 ft the water level would rise more than if your "tank" had been a swimming pool.
*November 16, 2014*

**Math**

PV = 800( 1 - 1.09^-10)/.09 Wow, let me know which bank pays you 9% in 2014.
*November 16, 2014*

**Advanced Algebra (Infinite Geometric Series)**

8.690909.... =8.6 + .09 + .0009 + .000009+... = 86/10 + .09/(1-.01) = 86/10 + .09/.99 = 86/10 + 9/99 = 86/10 + 1/11 = 478/55
*November 15, 2014*

**Math**

2 / ((cos(r^2 - s^2) / (sin(r^2 - s^2)) = 2 * (sin(r^2 - s^2) / (cos(r^2 - s^2) = 2 tan (r^2 - s^2)
*November 14, 2014*

**Math Please Assist**

sin^3 x + sinx cos^2 x = cosx sinx(sin^2 x + cos^2 x) = cosx sinx (1) = cosx sinx/cosx = 1 tanx = 1 x = 45° or x = 225° but you wanted to be between 0 and 180 so x = 45°
*November 14, 2014*

**math**

since you want cos 2Ø in terms of x from x+5 = 9sinØ bringing the 5 over would make things worse ... and no, you would not distribute the 9 over the 9sinØ - 5 I would proceed this way: sinØ = ( x+5)/9 now you will have to use one of the half-angle ...
*November 14, 2014*

**Pre-Calc/Trig**

quadratic --- x^2 term makes it that linear ----- x term makes it that cubic ------ from the x^3 term the highest exponent term establishes what kind it is
*November 14, 2014*

**Algebra**

slope = (-3-1)/(1-3) = 2 so it has to be one of the last two of your choices sub in (1,3) into y = 2x+5 ---> doesn't work sub in (1,3) into y = 2x - 5 ----> Yeahhh! so y = 2x-5 that is what bob had suggested to you, that is, try the points in the equations.
*November 14, 2014*

**math**

so in effect the ship went 41 + 15 or 56 north and 23 east. so d^2 = 56^2 + 23^2 = 3665 d =√3665 = 60.5 km
*November 14, 2014*

**math probability**

since the code > 400, your choice for the first digit is 6, you can put 10 different digits in the 2nd spot, and 10 different digits in the 3rd spot number of possible codes = 6x10x10 = 600 this would include 400, which cannot be used, since it must be greater than 400 so ...
*November 14, 2014*

**Math**

to the nearest 10 13---> 10 46 ---> 50 87 ---> 90 sum = 150 if you added them up like you did to get 146 , you have the actual answer, why bother estimating ? Besides, 146 rounded to the nearest tens is 150, not 160
*November 14, 2014*

**math probability**

I don't understand the question. In your first sentence, you are saying that there are only 9 dollars in the box.
*November 14, 2014*

**Intermediate Algebra**

simple interest formula: I = PRT, lets plug in our values 85 = 6000(R)(1/12) multiply both sides by 12 1020 = 6000R divide both sides by 6000 R = 1020/6000 = .17 or 17% You had the correct answer, but you should not just piece-meal bits and pieces from the equation.
*November 14, 2014*

**Intermediate Algebra**

sloppy use of the decimal place and your solution makes absolutely no sense. if x is the amount loaned at 6% ... .06x + .14(15000-x) = 1500 .06x + 2100 - .14x = 1500 -.08x = -600 x = 600/.08 = 7500 So $ 7500 was loaned at 6% and $7500 at 14% check: .06(7500) + .14(7500) = 1500
*November 14, 2014*

**MATH**

true if both are positve, or if both are negative. depends if one is + , the other - e.g 8/5 - 9/7 = 11/35 but 15/4 - 3/2 = 9/4 , still a mixed number
*November 13, 2014*

**Geometry**

let the size of the cut-out be x by x inches length of base = 24-2x width of base = 24-2x height = x V = x(24-x)^2 = x(576 - 48x + x^2) =576x - 48x^2 + x^2 dV/dx = 576 - 96x + 3x^2 = 0 for a max of V x^2 - 32x + 192 = 0 (x - 24)(x - 8) = 0 x - 8 or x = 24, but if x = 24, we ...
*November 13, 2014*

**Probability.. HELP!**

what is 36x35x34 ? Do you know why ?
*November 13, 2014*

**Math, Please Help!**

I will assume we are not distinguishing between small and capital letters. I will do one: TENNESSEE - 9 total, 2 N's , 4 E's, 2 S's total number of ways = 9!/(2!4!2!) = 3780 Can you see what I did ? OHIO ----> 4!/(2!) = 12 try the others.
*November 13, 2014*

**College Algebra**

If you mean (-10-6i) /( -9+9i) , then the brackets are essential (-10-6i) /( -9+9i) = (-10-6i) /( -9+9i) * (-9-9i)/(-9-9i) = (90 + 90i + 54i + 36i^2)/(81 -81i^2) = (54 + 144i)/162 = 1/3 + (8/9)i
*November 13, 2014*

**College Algebra**

type it this way: (-6 - √10)/(3 + 8√10) I will assume you are rationalizing (-6 - √10)/(3 + 8√10) = (-6 - √10)/(3 + 8√10) * (3 - 8√10)/(3 - 8√10) = (-18 + 48√10 - 3√10 + 80)/(9 - 640) = ( 62 + 45√10)/-631 = (-62...
*November 13, 2014*

**Calculus**

are you using the usual notation so that a(t) is acceleration, v(t) is velocity and s(t) is distance ?? I will assume you are a(t) = t^2 - 8t + 5 v(t) = (1/3)t^3 - 4t^2 + 5t + c s(t) = (1/12)t^4 - (4/3)t^3 + (5/2)t^2 + ct + k s(0) = 0 0-0+0+0+k=0 k=0 s(1) = 20 1/12 - 4/3 + 5/2...
*November 13, 2014*

**algebra**

looks like we are dividing by -2 each time, so ....
*November 13, 2014*

**algebra**

So a is always positive and b is always negative. What is a positive divided by a negative ?
*November 13, 2014*

**Algebra**

if f(x) = 4x^7+x^5+3x^2-2x+c f(-1) = -4 -1 + 3 +2 +c = 0 c = 0
*November 13, 2014*

**math**

Since the area of each time is 16 in^2, each side of the tile must be 4 inches the table is 6 ft by 6ft or 72 inches by 72 inches so we need 72/4 or 18 tiles along a side. since the table is square, the number of tiles needed = 18(18) 324 tiles
*November 13, 2014*

**Math**

I usually get rid of nasty decimals ... .1g+3.75m=7.36 --> 10g + 375m = 736 --> g = (736-375m)/10 8.2g+21m=73 ----> 82g + 210m = 730 10g +375m = 736 -times 410 --> 4100g + 153750m = 301760 82g + 210m = 730 -times 50 --> 4100g + 10500m = 36500 subtract them: ...
*November 13, 2014*

**math**

I think Bob has a typo in dividing x+y+z by 2 instead of 3 x+y+z+ (x+y+z)/3=360 3x+3y+3z + x+y+z = 1080 4x+4y+4z = 1080 x+y+z = 270
*November 13, 2014*

**Algebra 2**

3x^2 - 24x + 45 = 0 remember Steve told you about all that "zero stuff" ? divide each term by 3 x^2 - 8x + 15 = 0 can you think of 2 numbers that add up to -8 and multiply to get 15 ? I am thinking -3 and -5 so (x-3)(x-5) = 0 x-3=0 ----> x = 3 or x-5 = 0 ----> ...
*November 13, 2014*

**math**

Proof for all values: let a+b+c+d+e = S let M be the average M = S/5 5M = S then S/M = 5/1 or S : M = 5 : 1
*November 13, 2014*

**Math**

correct
*November 13, 2014*

**algebra. help!**

first one: y = 2^x why did you possible pick c) not a single one of the pairs given satisfies that equation. It is clearly y = (x+3)^2 , that is, d)
*November 13, 2014*

**Algebra**

number of $1 --- n number of $2 --- n+11 number of $3 --- n-18 now for the "value" : 1n + 2(n+11) + 3(n-18) = 100 n+2n+22 + 3n-54 = 100 6n = 132 n = 22 then n+11 = 33 n-18 = 4 so 22 $1 bills , 33 $2 bills and 4 $3 bills check: 22 + 66 + 12 = 100 Yeahh
*November 13, 2014*

**Algebra**

surely you can replace x with 2 and add 2+6
*November 13, 2014*

**Algebra**

in h(x) = −9x^3+3x^2−2x+2 they are in order of decreasing degree
*November 13, 2014*

**Algebra**

h(x) = −9x^3+3x^2−2x+2 why did you put commas between terms in your answer ?
*November 13, 2014*

**math**

cost = 16m + 1895 , where m is the number of miles and cost is in cents 16m + 1895 = 5000 16m = 3105 m = appr 194 miles check: 194(.16) + 18.95 = 49.99
*November 13, 2014*

**Algebra 2**

As Morgan pointed out, your left side is a perfect square (x+4)^2 = 16/9 x+4 = ± 4/3 x = 4/3 - 4 = -8/3 or x = -4/3 - 4 = -16/3 your signs were wrong
*November 13, 2014*

**algebra**

tom has x stickers Matt has 6x stickers there must have been a total of 140 stickers x + 6x = 140 7x = 140 x = 20 Tom has 20 and Matt has 120 So Matt has to give 50 of them to Tom check: Tom: 20+50 = 70 Matt: 120-50 = 70 Yeahhh
*November 13, 2014*

**Trig/Pre-Calc**

try x = ±1 , ±2, ±4, ±8 I got x = 8 to work for me so after a sythetic division, I got (x-8)(15x^2 + x - 2) = 0 (x-8)(3x-1)(5x + 2) = 0 x = 8 , 1/3 , -2/5
*November 13, 2014*

**math**

same type of problem as your previous one
*November 13, 2014*

**math**

What is 9 ÷ (3/8) ?
*November 13, 2014*

**chin**

That is a "serious" problem I will use A for ace F for facecard and L for non-ace, non-face (L for loser) I will also assume that none of the 4 cards drawn in a game are returned to the deck, but they would be returned after a game is played. so the possible ...
*November 13, 2014*

**maths algebra**

I think you are referring to this earlier post by you http://www.jiskha.com/display.cgi?id=1415787409 I agree with Steve's answer, I subbed his answer back in the original equation, and it worked. Steve's solution was correct, perhaps you typed it incorrectly. As to ...
*November 13, 2014*

**math**

Just translate the English into Math "Half the total number of balls are pink. " ----> p = (1/2)(r+b+g+p) 2p = r+b+g+p p = r+b+g , #1 "One-fourth of the number of green balls equals one-third of the numher of blue balls. " ----> (1/4)g = (1/3)b 3g = ...
*November 13, 2014*

**Algebra**

amount = 19 (1/2)^(150/97) = appr 6.5 g
*November 13, 2014*

**math**

look at Steve's solution here http://www.jiskha.com/display.cgi?id=1382123644 then change the numbers to fit your problem
*November 12, 2014*

**math**

at a time of t minutes, let the radius of the water level be r cm let the height of the water level be h cm by ratios: r/h = 1.75/6 1.75h = 6r r = 1.75h/6 = 7h/24 V = (1/3)π r^2 h = (1/3)π(49h^2/576)h = (49π/1728) h^3 dV/dt = (49π/576) h^2 dh/dt without ...
*November 12, 2014*

**calculus**

total distance = 24 + 24(.95) + 24(.95)^2 + .... an infinite GS, where a = 24 and r = .95 sum(all terms) = a/(1-r) = 24/(1-.95) = 24/.05 = 480 metres
*November 12, 2014*

**Calculus**

nope, I have no idea how you got that. use the product rule, y = x secx y' = x(secx)(tanx) + secx or = x(1/cosx)(sinx/cosx) + 1/cosx = xsinx/cos^2 x) + 1/cosx or = (xsinx + cosx)/cos^2 x so slope = (π/4)(√2/2) + √2/2)/(1/2) = .....
*November 12, 2014*

**finance math**

Assumption: the rate stays at 7% throughout her 31 years of deposits and the 15 years of withdrawals. (What happens after the 15 years of retirement and her money is used up ? ) let her payment + employers share be $x per year x( 1.07^31 - 1)/.07 = 30000(1 - 1.07^-15)/.07 you ...
*November 12, 2014*

**Math**

so in your equation, y is the number of words and x is the number of minutes so set y = 2500 50x - 25 = 2500 50x = 2525 x = 50.5 so it will take 50.5 minutes or 50 minutes and 30 seconds.
*November 12, 2014*

**Algebra**

Trish, since subtraction only involves "like" terms, and g(x) does not contain any x^4 term, nothing can happen to the x^4 term of f(x) so your result still contains the x^4 term , and thus is a polynomial of degree 4
*November 12, 2014*

**Math**

Well, I would suggest you do each division and see.
*November 12, 2014*

**Math**

Your question asked for the slope, you gave the equation as an answer. I can tell that you found the slope to be 35, which is correct. Also the equation is correct
*November 12, 2014*

**Algebra 2**

Neither equation you state is a quadratic equation for the first, we could attempt to write it as 0x^2 + 5x - 6 = 0 , but when we attempt to use the formula x = (-b ± √(b^2 - 4ac) )/2a we get x = (-5 ± √(25 - 0)/0 = 0/0 , which of course causes all ...
*November 12, 2014*

**Math**

good job !
*November 12, 2014*

**Math**

yes, I would get y - 100 = (100/3)(x - 3) times 3 3y - 300 = 100x - 300 100x - 3y = 0 or y = (100/3)x
*November 12, 2014*

**Math**

I would simplify that ... 50/1.5 = 100/3 Normally we don't mix decimals with fractions, use either one or the other. your answer technically is correct
*November 12, 2014*

**Algebra**

If you were to fully expand this, your unsimplified line would consist of 27 terms - that is, any combination of terms in the first bracket times any term in the second bracket times any term in the third bracket the only way to get x^3 is to have -3 from the first times -3x ...
*November 12, 2014*

**Algebra**

so ( p(x) )^3 = (x^4-3x+2)(x^4-3x+2)(x^4-3x+2) now consider which combination can produce a term ending in x^3 ??
*November 12, 2014*

**Algebra**

so f(x) has to contain an x^4 term and g(x) does NOT contain an x^4 term so what happens to that x^4 term in f(x) when g(x) is subtracted from it ???
*November 12, 2014*

**math**

let the base be x by y m V = (x)(y)(1) = xy xy = 9 y = 9/x cost = 50xy + 60xy + 2(40x) + 2(40y) = 110xy + 80x + 80y = 110x(9/x) + 80x + 720/x = 110 + 80x + 720/x d(cost)/dx = 80 - 720/x^2 = 0 for a min of cost 80x^2 = 720 x^2 = 9 x = 3 then y = 9/3 = 3 the box should be 3 by 3...
*November 12, 2014*

**Math Help!!!**

1. 1/2 is rational, thus real (any rational is automatically real) -1.016879413894 --- can't tell from the way it was typed. No repetition is apparent, but no indication is given that it continuous. If it terminates the way it was typed, then it is rational the last two ...
*November 12, 2014*

**Algebra**

amount = 4500(1 + .045/365)^3650 = 7057.21 or $ 7057 to the nearest dollar
*November 12, 2014*

**Math**

Each of the sides must be 10 m The longer diagonal creates an isosceles triangle with angles 30,30 and 120° Several ways to do this 1. Construct a perpendicular which will bisect the diagonal. Let the diagonal be 2x then x/10 = cos30° x = 10cos30 = 8.66.. 2x = 17.32 m ...
*November 12, 2014*

**ap calc**

so far ok -3sin(x)-2cos(x)=0 3sinx = -2cosx sinx/cosx = -2/3 tanx = -2/3 construct your triangles in quad II and IV for both the hypotenuse is √13 in quad II y = 3(-3/√13) - 2(2/√13) = -13/√13 in quad IV y = 3(3/√13) -2(-2/√13) = 13/√...
*November 9, 2014*

**ap calc**

First of all, since (1,4) is on the curve, 4 = a + b dy/dx = a - b/x^2 = 0 for a max or min but we are told that this is true when x = 1 so a - b/1 = 0 a - b = 1 add them, 2a = 5 a = 5/2 sub back into the first equation, a+b=4 5/2 + b = 4 b = 3/2 a = 5/2 , b = 3/2
*November 9, 2014*

**Math**

by Pythagoras, you can find MW = 12 then cosW = 12/13
*November 9, 2014*

**college algebra**

same post
*November 9, 2014*

**college algebra**

x^4 +12x^3 +10x^2-9x+9x+22=0 I suspect a typo, why would you have two x terms without combining them?
*November 9, 2014*

**calculus**

y' = (4x+3)^5 (-4)(5x+2)^-5 (5) + (5x+2)^-4 (5)(4x+3)^4 (5) = -20(4x+3)^5 (5x+2)^-5 + 20(4x+3)^4 (5x+2)^-4 take it further if there is need by taking out a common factor of 20(4x+3)^4 (5x+2)^-5
*November 9, 2014*

**Math - Word problem**

Mary, your problem is a variation of the famous "spider and fly" problem. Here is a webpage that has the same concept, you have an electrical outlet and box instead of spider and fly. http://mathworld.wolfram.com/SpiderandFlyProblem.html Use Steve's instructions ...
*November 9, 2014*

**Algebra 2**

you just proved my point, you forgot to switch back to one of your other names
*November 9, 2014*

**Algebra 2**

Don't change names, stick to one name follow the same steps I showed you yesterday for the same type of problem http://www.jiskha.com/display.cgi?id=1415491412 expand first, then bring everybody to the left and factor. Remember the right side has to be zero.
*November 9, 2014*

**Algebra 2**

follow the same steps I showed you yesterday for the same type of problem http://www.jiskha.com/display.cgi?id=1415491412 expand first, then bring everybody to the left and factor. Remember the right side has to be zero.
*November 9, 2014*

**calculus**

follow the steps I just showed you for your previous problem (same thing)
*November 9, 2014*

**calculus**

f(f(x)) = f(4x^2 - 1) = 4(x^2 - 1)^2 - 1 don't know if you have to expand that, leave that up to you g(f(x)) = g(4x^2 - 1) = 4/(4x^2 - 1)
*November 9, 2014*

**average**

Reverse your thinking. How do you think they found the average of those 4 numbers to be 36 ?
*November 9, 2014*

**Calc**

notice the point (4,0) does not lie ON the curve. So your sketch should show that. let that point be (a,b) so we know b = √a or a = b^2 dy/dx = (1/2)x^(-1/2) or 1/(2√x) so at the point (a,b) the slope of the tangent is 1/(2√a) I will use the property that at ...
*November 9, 2014*

**math**

number of men --- m number of women --- w number of children --- c m+w+c = 180 , #1 m = 2w , #2 w = 3c , #3 from #2 , w = m/2 then in #3, 3c = w c = (1/3)w = (1/3)(m/2) = m/6 back in #1 m+w+c = 180 m + m/2 + m/6 = 180 times 6 6m + 3m + m = 1080 10m= 1080 m = 108 then w = m/2...
*November 9, 2014*

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