Monday
September 26, 2016

Posts by Steve

Total # Posts: 44,072

Calculus AB
well, you want cos x = -0.4 so, x will be an angle in QII or QIII Your reference angle is arccos(0.4) = 66.4° so, x will be 180±66.4°
July 29, 2016

math
looks good to me Make sure you specify mm^3 for volume. That's a dang small prism, to be sure...
July 29, 2016

math
A(1+.12*5) = 160000
July 29, 2016

Calculus AB
it's an even multiple of 2pi, so the functions are the same as for 0.
July 29, 2016

Calculus AB
recall that log_a(b) = ln(a)/ln(b) So, converting everything to natural logs (or any set of logs with a common base), ln3/ln25 x + ln7/ln2 y = ln27/ln5 ln8/ln7 x + ln5/ln3 y = ln2/ln49 Now just solve the system as usual. It's messy, but it's just numbers. If you don&#...
July 29, 2016

statitics
just list the cases: P(WL) = 0.60*0.25 P(LW) = 0.40*0.55 Since they are mutually exclusive, P(WL)+P(LW) = 0.37
July 29, 2016

math
Divide 32 by the number of colors. Then count over in the list the remainder. For example, your list has 5 colors 32/5 = 6 R2 So, there are six complete cycles, with 2 left over. The 32nd stripe is thus blue. If you only wanted 4 colors, the do that division instead. A zero ...
July 29, 2016

luderitz
not following instructions, as in the subject of your post.
July 29, 2016

Math
.85x +.60*150 = .80(150+x)
July 29, 2016

math
x = (90-x)-8
July 29, 2016

Math
35 m/s * 1km/1000m * 3600s/hr = ? km/hr
July 29, 2016

science
If the distance is x meters, then since time = distance/speed, x/55 + x/330 = 7 x = 330m Now, the problem is that the bullet will drop 176m in the 6 seconds spent in the air. So, now we have to include the angle of the trajectory, which complicates matters some.
July 29, 2016

Maths
Review your sine rule. It is then clear that sinθ = √(15^2-6^2)/15 It might have been easier to calculate using cosθ = 6/15
July 29, 2016

Accounts
2000(1+.06/2)^(2*6)
July 29, 2016

Stats
Your Z table tells you that about 97% of the population lies below the mean + 1.88 std. so, ...
July 29, 2016

Physics
If I can get by the sloppy typing, it is clear that h^2 + 2^2 = 9^2
July 29, 2016

math
the number who passed either or both is .80+.85-.75 = 0.90 So, 10% of x students failed both: 45 = 0.10x . . .
July 29, 2016

PACE INter Science Colldege
100km/hr * 1L/10km * 1hr/3600s * 1000cm^3/L = 27.77 cm^3/s
July 29, 2016

Math
the linear ratio is √25:64 = 5:8 the volume ratio is thus 5^3:8^3 = 125:512 or, 250:1024
July 28, 2016

math
If the dimensions are x and y, then we have √(x^2+y^2) = x+8 xy = 60 You can grind out the solution, but I think you can recognize which factors of 60 form a convenient right triangle that works, no?
July 28, 2016

Calculus
dang those typos, yeah? 64 works much better.
July 28, 2016

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

Science
🖕🏽
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

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