Wednesday
July 27, 2016

Posts by steve

Total # Posts: 42,128

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

Math
let u = 9^x then, 9^(2x) = (9^x)^2 = u^2 Thus all you have is u^2+4u = 21 u^2+4u-21 = 0 (u+7)(u-3) = 0 so, u = -7 or u=3 But, u = 9^x ...
July 24, 2016

Math
this is just a quadratic in 9^x. So, it factors out as 9^(2x) + 4(9^x) - 21 = 0 (9^x + 7)(9^x - 3) = 0 9^x cannot be -7, so you are left with 9^x = 3 x = 1/2
July 24, 2016

Maths
do a synthetic division on each polynomial using x-p. If p is a common root, then both remainders will be zero. Eliminate p and you will wind up with a polynomial in a,b,c. Solve for b.
July 24, 2016

Some Please Help me - PreCalc
All you need to do is show that x^2+y^2=1. Don't forget your Algebra I now that you're in pre-cal! (√31/7)^2 = 31/49 (-3√2/7)^2 = 18/49 Looks like they add up to 1, so the point is on the unit circle.
July 24, 2016

Maths
google is your friend. I found http://math.stackexchange.com/questions/1629163/how-to-find-derivative-of-sin-sqrtx-using-difference-quotient
July 24, 2016

Calculus
when x=3, y=4 2x dx/dt + 2y dy/dt = 0 or, losing the factor of 2, x dx/dt + y dy/dt = 0 Now just plug in your numbers.
July 24, 2016

Algebra
well, did you actually try it? 7/6 < 5 check 5 < 1/(1/6) = 6 check So, yes, that works.
July 24, 2016

Algebra
x + 1.28x = 3420
July 24, 2016

mathematics
42
July 24, 2016

Math
49 and 0
July 24, 2016

Math
x(12-x)
July 24, 2016

MATHEMATICS
4 years ago, the average age was 22. So, now it is 26. After the adoption, since the average age now is 24, The new kid is x years old, where 26*4+x = 24*5 x = 16 So, he was 14 when adopted 2 years ago.
July 24, 2016

Physics
angular velocity: 2π/40 = π/20 rad/s speed: 40πm/40s = π m/s velocity: -80m/40s = -2 m/s in the direction from start to finish.
July 24, 2016

physics
p = mv now just plug in your numbers
July 24, 2016

Math
Assuming the usual sloppiness with parentheses, I parse you equation as (x-1)/(x^2-9) + 1/(x-3) = 2/(x+3) using a common denominator of (x+3)(x-3), we have (x-1) + 1(x+3) - 2(x-3) -------------------------- = 0       (x-3)(x+3) assuming x is not 3...
July 24, 2016

math
I cannot parse un first second through which height it will move ??
July 24, 2016

maths
6x + 4y*-3x + 5x - 2x*3y do * first, so 6x - 12xy + 5x - 6xy Now add like terms: 11x - 18xy
July 24, 2016

Math
distance = speed * time, so if the van's speed is v, then v-28 = 2/3 v
July 24, 2016

Math
Suppose n groups of beads were used for the necklace. Then 3n yellow beads and 2n blue beads were used. So, counting just the blue beads, 35 + 2n = 4*3n This is not possible if only whole groups of 2 blue and 3 yellow beads were used.
July 24, 2016

Maths & numeracy
compare $6.48/250g = $.0259/g vs $10.65/375g = $0284/g
July 24, 2016

Maths
1/x = logn(a) 1/y = logn(c) (x-y)/(x+y) = (1/y - 1/x)/(1/y + 1/x) = logn(c/a)/logn(c*a) logb(c)-logb(a) = logb(c/a) logb(c)+logb(a) = logb(c*a) The two ratios are equal.
July 23, 2016

math
LCM(6,10) = 30
July 23, 2016

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