Wednesday

August 31, 2016
Total # Posts: 42,949

**Calculus**

x+y=64 z = xy^3 = (64-y)y^3 = 64y^3 - y^4 dz/dy = 192y^2 - 4y^3 = 4y^2(48-y) I think the way is now clear, right?
*July 28, 2016*

**jeez - get it right, willya?**

and stop posting it!
*July 28, 2016*

**algebra - eh?**

how's that again? The product of two consecutive integer is 5 three times the larger integer
*July 28, 2016*

**Math**

just remember that revenue = price * no.tickets.sold You can use that to answer all these questions. Give it a try, and come back if you get stuck. also, recall that the vertex of a parabola ax^2+bx+c is at x = -b/2a. For R(x), that is where the maximum revenue occurs.
*July 28, 2016*

**physics**

v = √(2as) = √(2*9.8*20) = 19.80 m/s Now use that to answer the other question.
*July 28, 2016*

**math**

can't see hwy you don't just write the fractions, like 1/3, 2/√5, etc. Anyway, since volume is length * width * height then if one or more of those dimensions are scaled by a factor of r,s,t respectively, then the new volume is (length*r)*(width*s)*(height*t) = (...
*July 28, 2016*

**Algebra 1**

After n years, v = c(1-r)^n = 20000 * 0.79^n no need to subtract from anything, unless you want to see how much its value has declined. 6154.11 is the value after 5 years.
*July 28, 2016*

**Maths**

try using the sum-to-product formulas. If you get stuck, come on back and I'll see what we can do with what you have so far. I see google has some good discussions.
*July 28, 2016*

**Maths**

cos3x = cosx(2cos2x - 1) similarly, cos6x = cos2x(2cos4x - 1) I think you can see where this is going, right?
*July 28, 2016*

**Maths**

google is your friend many proofs online
*July 28, 2016*

**pre cal**

the asymptotes mean y = ??? / (x+2)(x-1) y(0)=0, so y = ax / (x+2)(x-1) y(2) = 12, so 12 = 2a/4 a = 24 y = 24x / (x+2)(x-1)
*July 28, 2016*

**pre cal**

vertical asymptote at x=6 and a horizontal asymptote means y = a(x-b)/(x-6) + c y(5) = 0, so b=5 y = a(x-5)/(x-6) + c y(0) = -5/6 and y(∞) = -1, so 5/6 a + c = -5/6 a + c = -1 1/6 a = -1/6 a = -1 c = 0 y = (5-x)/(x-6)
*July 28, 2016*

**math**

2 + 2 sinθ = 3 cos^2θ 2 + 2sinθ = 3 - 3sin^2θ 3sin^2θ + 2sinθ - 1 = 0 (3sinθ-1)(sinθ+1) = 0 sinθ = 1/3 sinθ = -1 so, there are two solutions for sinθ = 1/3 (QI and QII) and one solution for sinθ = -1
*July 28, 2016*

**basic maths trignometry**

secx - tanx = 1/cosx - sinx/cosx = (1-sinx)/cosx now use the double angle formulas to make that 1 - 2sin x/2 cos x/2 ------------------------- 2 cos^2 x/2 - 1 divide by cos^2 x/2 to get sec^2 x/2 - 2tan x/2 ----------------------------- 2 - sec^2 x/2 1+tan^2 x/2 - 2tan x/2...
*July 28, 2016*

**math**

5*4/5 = 4
*July 28, 2016*

**Math**

45/9 = x/12 x = 60
*July 28, 2016*

**math**

Oops. r=16% I calculated with r as the 6-month interest rate.
*July 28, 2016*

**math**

6250(1+r/2)^2 = 6760 r = 8%
*July 28, 2016*

**Maths**

For ease of reading, I'll just use s for sinx and c for cosx (1+s-c)/(1+s+c) = (1+s-c)^2/[(1+s)^2-c^2) = (1+s-c-sc)/(s+s^2) = (1-c)(1+s)/(s(1+s)) = (1-c)/s That means that [(1+s-c)/(1+s+c)]^2 = (1-c)^2/s^2 = (1-c)(1-c) / (1+c)(1-c) = (1-c)/(1+c)
*July 27, 2016*

**Maths**

I assume you mean arctan(x)+arcsin(x)=3/4 π well, you know that π/4 + π/2 = 3/4 π so, x=1 the hard way: sin(arctan(x)+arcsin(x)) = 1/√2 sin(arctan(x))cos(arcsin(x)) + cos(arctan(x))sin(arcsin(x)) = 1/√2 Now draw the right triangles for arctan(x...
*July 27, 2016*

**pre cal**

f(x) = a(x+5)(x-2)(x-4) f(-10) = a(-5)(-12)(-14) = -840a = -4 a = 1/210 f(x) = 1/210 (x+5)(x-2)(x-4)
*July 27, 2016*

**Algebra**

Well, you found the midpoint wrong. It is (-7.5,2.5) unless there's a typo in the coordinates. clearly x+y = -12 is wrong, since -8+4 = -4 That should have been your first clue. Using correct midpoint, the slope is -3. So, the answer is y-4 = -3(x+8) y-4 = -3x-24 3x+y = -20
*July 27, 2016*

**Maths**

I'll get you started. These problems are all about the same. The percent change is the amount pf the change divided by the starting amount. In this case, the two changes are (100-120)/120 = -20/120 = -1/6 = -16.67% (80-100)/100 = -20/100 = -20%
*July 27, 2016*

**Geometry**

it's a dilation, not a translation. for a dilation, each coordinate is multiplied by the scale factor.
*July 27, 2016*

**Algebra**

sina = cos(π/2-a) cosa = sin(π/2-a) 1+sina+icosa = 1+cos(π/2-a) + i sin(π/2-a) = 1 + cis(π/2-a) There is no simple cis(x) form because of that pesky 1.
*July 27, 2016*

**Math**

6n - 2(n-1) = 4n+2
*July 27, 2016*

**math**

(x)+(2x-32)+(x+18) = 534 Solve for x, and then the 3 parts.
*July 27, 2016*

**F/maths**

let the time spent on XY and YZ be a and b, respectively. Then on XY: s = 5a + a^2; v@Y=5+2a on YZ: s = (5+2a)b - 7/4 b^2; v@Z=0 Then we have 5a + a^2 + (5+2a)b - 7/4 b^2 = 475 5 + 2a - 7/2 b = 0 Just solve for a and b, and then you can answer the questions.
*July 27, 2016*

**maths - eh?**

eh? √16 = √4 ?
*July 27, 2016*

**Math**

This can also be seen by noting that a^2-b^2 = (a+b)(a-b) In this case, since the numbers are consecutive, that is just S*1 = S
*July 27, 2016*

**chemistry**

counting the moles, if there are x L of 6M HCl, then 6x + 2(2-x) = 3*2
*July 27, 2016*

**maths**

Assuming you meant 6 liters of paint, then he needs 5m*3m * 6L/10m^2 = 9L That's for one wall. No idea how many walls there are.
*July 27, 2016*

**Science**

google is your friend.
*July 27, 2016*

**Maths**

well, the volume is 2.5*20*1.5 = 75m^3 Your mission, should you choose to accept it, is to convert that to liters.
*July 27, 2016*

**Math**

2/3 x = -28
*July 27, 2016*

**SPANISH**

¿Y qué?
*July 27, 2016*

**maths**

a(1+2r) = 8320 a(1+3.5r) = 9685 a = 6500
*July 26, 2016*

**Math**

g(x) = f(x)+5, so it is shifted up 5 units. or, f(x) = 2x-3 g(x) = 2x+2 = 2(x+5/2)-3 So, g(x) is f(x) shifted left 5/2
*July 26, 2016*

**Geometry - incomplete**

Can you not see how incomplete is your description?
*July 26, 2016*

**Math**

8cis30° + 8cis120° = 8√2 cis75° or, 8<√3/2,1/2>+8<-1/2,√3/2> = 4<√3-1,√3+1> either way, the y-component is 4(1+√3) ≈ 10.928
*July 26, 2016*

**math**

what do you mean by "their age" ?
*July 26, 2016*

**Algebra**

When you do the synthetic division, there will be an "a" in the remainder. The remainder is -52+a So, you set -52+a = -4 and get a=48 The bottom row of the division is 2 -15 26 -52+a
*July 26, 2016*

**Algebra**

As it is written, f(-2) = 80+a So, 80+a = -4 means a = -84 But, there is apparently a typo in f(x). If we set f(x) = 2x^3−11x^2−4x+a f(-2) = -52+a = -4 so, a = 48 So, how did you come by your results? I showed you mine. Show me yours.
*July 26, 2016*

**Algebra**

By the Remainder Theorem, f(-2) = -4. So, evaluate f(x) at x = -2 and solve for a. Or, do a synthetic division and see what the remainder is. Set that equal to -4 and solve for a.
*July 26, 2016*

**maths**

If w games were won, then 15-w were lost, so the points add up as 5w - 2(15-w) = 54 So, solve for w.
*July 26, 2016*

**math**

5C3 = 10
*July 26, 2016*

**Math**

If Alger is x, then Abigail is x+7. So, just solve for x in x(x+7) = 144 Note that 144 = 9*16
*July 26, 2016*

**Maths**

clearly, 0.25L which is the increase in volume.
*July 26, 2016*

**physics**

(a) You want 1/2 meve^2 = 1/2 mpvp^2 so that means that ve^2/vp^2 = mp/me = 1836 ve = √1836 vp (b) that would of course be 1836K
*July 26, 2016*

**Trigo**

Draw a diagram. Review your basic trig functions Now it is clear that the distance x between the ships is x = 30cot23° - 30cot28°
*July 26, 2016*

**math**

or, equivalently, 1/A + 1/B = 1/8 6/8 + 9/B = 1
*July 26, 2016*

**math**

well, it's 333 to the nearest integer. whether that's the nearest meter is something else entirely.
*July 26, 2016*

**Physics**

looks good, but I'd have gone from 180 = 36a/2 to 180 = 18a
*July 26, 2016*

**Maths**

posted the same gibberish twice and still no question. what the heck do you mean by whose he=5cm each=6cm
*July 26, 2016*

**Maths**

ok now what?
*July 26, 2016*

**maths**

28*40 = x(40+16)
*July 26, 2016*

**Math**

each side is 17, so its height is 17sinθ where θ is the acute angle between its sides. Thus, 17 * 17sinθ = 240 sinθ = 240/289 Now you have θ, and the diagonals are found using the law of cosines: d^2 = 17^2 + 17^2 ± 2*17^2 cosθ = 2*17^2 (1&...
*July 25, 2016*

**pre cal**

this is just a quadratic in 2^x, since 2^2x = (2^x)^2 So, it factors into (2^x-3)(2^x-2) = 0 So, 2^x = 2 or 3 That means x = 1 or log2(3)
*July 25, 2016*

**physics **

a rock is dropped from a height of 20m above the ground when it hits the ground it leaves a hole 10cm deep. With what speed does the rock hit the ground, what is the magnitude of the rock's deceleration after it hits the ground
*July 25, 2016*

**physics**

a train moving at 35m/s slows down to 20 m/s over the course of 1 minute what distance does the train cover during this time, what is the trains acceleration during this time, if the train continued to slow down with the same acceleration how much more time would it take to ...
*July 25, 2016*

**physics**

a woman drives at a speed of 20m/s for part of a trip and at a speed of 30m/s for the rest of the trip if she spends 10 minutes driving at each speed determine her average speed for the full trip. If instead she drives 10 kilometers at each speed determine her average speed ...
*July 25, 2016*

**pre cal**

assuming logs base b, we have log(24) = log(2^3 * 3) = 3log2+log3 = 3*0.264 + 0.419 = 1.211 log(100) = log(10^2) = 2log10 = 2log(2*5) = 2(log2+log5) = ... log(5b^3) = log5 + 3logb = 0.614 + 3 = 3.614 since logb(b) = 1
*July 25, 2016*

**pre cal**

I'll do one. You just need to remember that log(ab) = log(a) + log(b) log(a^n) n log(a) So, (c) can be done as follows: log4(64^k) = log4(4^3^k) = log4(4^(3k)) = 3k since log_b(b) = 1 for any b I think you have garbled (d). Try using some parentheses to clarify, or try ...
*July 25, 2016*

**@again?**

Check previous post ... I know it's been a long time (4 minutes), so you'd naturally be impatient. not
*July 25, 2016*

**pre cal**

regardless of the base, log15+log405-5log3 = log(15*405/3^5) = log(25) Since we are using base 5, log_5(25) = 2 since 5^2 = 25
*July 25, 2016*

**Math**

you have mi/hr You want ft/s 1 hour = 3600 seconds 1 mile = 5280 feet So, 1mi/hr = 5280 ft/hr = 5280ft/3600s = 5280/3600 ft/s your speed is 27 mi/hr, so that is 27*5280/3600 = 29.6 ft/s You can always multiply by 1 without changing anything. Since 1 mi = 5280 ft, that means ...
*July 25, 2016*

**Math**

27mi/hr * 5280ft/mi * 1hr/3600s = ? ft/s
*July 25, 2016*

**Chemistry**

figure the moles check the balanced equation to see how many moles of NO2 are produced. Recall that 1 mole fills 22.4L at STP
*July 25, 2016*

**algebra**

well, just remember that 1/i = -i since i^2 = -1 and the rest should be easy to work out.
*July 25, 2016*

**Math**

If the sides of the rectangle are x and y, then since the diameter of the circle is the diagonal of the rectangle, x^2+y^2 = d^2 The area is xy. The area squared A = a^2 = x^2y^2 = x^2 (d^2-x^2) = d^2 x^2 - x^4 a has a maximum where A does, so since dA/dx = 2d^2 x - 4x^3 = 2x(...
*July 25, 2016*

**Physics**

Interesting, how showing your work means showing the work!
*July 25, 2016*

**Pyshics**

since the distance is proportional the the square of the speed, 3*speed ==> 9*distance
*July 25, 2016*

**Normal**

can prove graphabload
*July 25, 2016*

**math**

sum the values divide by how many there are.
*July 25, 2016*

**math - junk**

sorry - lost track of where I was on the screen. But, the info is there/
*July 25, 2016*

**math**

since the denominator is (x+1)(x+2) you'd expect to see vertical asymptotes at x= -1 and -2 But the numerator is (x-1)(x+2)(x-3) so at everywhere except x = -1,-2 f(x) = (x-1)(x+2)(x-3) / (x+1)(x+2) = (x-2)(x-3) / (x+1) = x-5 + 8/(x+1) So, there is a slant asymptote of y=x...
*July 25, 2016*

**Algebra**

17C12 = 17C5 = 6188
*July 25, 2016*

**Physics**

Just solve for q2 in the formula F = (k q1 q2)/d^2 There is an interactive calculator at http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elefor.html
*July 25, 2016*

**trigonometry**

come on you know that sin²(u) + cos²(u) = 1 so, the equation reduces to sin²(3x) + cos²(3x) - (sin²(x) + cos²(x)) = 0 1 - 1 = 0
*July 25, 2016*

**trigonometry**

sin²(3x) + cos²(3x) = 1 1 + sin²(x) - cos²(x) = 2sin²(x) not zero I suspect you have a typo. A true assertion is sin²(3x) + cos²(3x) - sin²(x) - cos²(x) = 0
*July 25, 2016*

**Math**

just put a 2 in for every x: 7*2^3 + 4 = 7*8 + 4 = ...
*July 25, 2016*

**Math**

don't waste our time posting the exact same problem twice. It is clearly a physics problem, so don;t try to disguise it by calling it just math. Anyone experienced in physics will open the first posting, and help if they can. Anyone not able to help in physics (in this ...
*July 25, 2016*

**math**

Try reading a few of these items. They will be helpful, and explain more thoroughly than you will find here. https://www.google.com/search?q=least+common+multiple&ie=utf-8&oe=utf-8
*July 25, 2016*

**Math**

Type your stuff in at wolframalpha.com. Use parentheses to ensure that its interpretation is what you meant. Check your answer against the one presented. If you can't figure out how to get there, come on back for further help. For #1, see http://www.wolframalpha.com/input...
*July 25, 2016*

**Gemotery**

I disagree. But, I will say that M' = (2,4)*0.8 = (1.6,3.2) You can find others the same way.
*July 25, 2016*

**Chemistry**

how many moles NaOH? how many liters of solution? M = moles/liter
*July 25, 2016*

**physics**

First, check that it hasn't yet hit the ground. Finding it has not, then get the resultant of the horizontal and vertical velocities √(10^2 + (9.8*3)^2) at an angle of 71° below the horizontal
*July 25, 2016*

**business math**

1200(1+.086*6) + 500(1+.086*3) or 1200(1+.086*3) + 1700(1+.086*3) = 2900(1+.086*3)
*July 25, 2016*

**Mathematics @Tris**

Interesting answer. How did you arrive there?
*July 25, 2016*

**Mathematics**

√(61^2 + 28^2) = ...
*July 25, 2016*

**Mathematics**

40/(3+5) = 40/8 = ...
*July 25, 2016*

**math**

6*8^2 = 6*64 = ...
*July 24, 2016*

**math**

A(4) = 80/3 = 26.6666 A(4.01) = 26.6999 slope ≈ .0333/.01 = 3.33 As always, the slope is the rate of change. In this case, how fast the drug is being absorbed 4 <time units> after ingestion.
*July 24, 2016*

**geometrey**

pretty sure it's area.
*July 24, 2016*

**Java**

still Math
*July 24, 2016*

**math**

a graphical or numerical method would do the trick, if you don't have calculus to help.
*July 24, 2016*

**math**

(a) revenue-cost = profit y = p(-(p+5)(p-17)) - (75+12(-(p+5)(p-17))) = -(p^3-24p^2+59p+1095) (b) R>C means P>0 The roots are at -5.2, 13.1, 16.1 From what you know about the shape of cubics, P>0 in the interval (13.1,16.1) (c) y' = -(3p^2-48p+59) y' = 0 at p=...
*July 24, 2016*

**MATH**

check your previous post before reposting the same question: http://www.jiskha.com/display.cgi?id=1469374770
*July 24, 2016*

**Java**

Math class
*July 24, 2016*