Thursday
July 24, 2014

Posts by STEVE


Total # Posts: 23,941

Math
V = 1/3 Bh 78.6 cm^3 = 1/3 B(6 cm) B = 39.3 cm^2

alegbra
just solve for p in p(1+.055/4)^(4*3) = 990 8y 155d = 8.43 years, so p*e^(.0855*8.43) = 225500

math
30*9 = 270 So, add 270-250 the rate the other workers have is just noise.

geometry - incomplete
BA + AC = BC 7w-12 + 6w-14 = BC 13w-26 = BC Now you need to know what BC is to find w. I suspect that BC is a multiple of 13, no?

5th grade math
to double the volume, double any one (and ONLY one!) of the dimensions. SO, your mission, should you choose to accept it, is to pick the dimension which will produce the most practical shape for the new box.

ALG
well, plug in -2x+3 for y: -2x+3 = x^2-x-3 x^2+x-6 = 0 (x+3)(x-2) = 0 Looks like two solutions to me. I'm sure you can figure them out, eh?

Mahts
300 = (100+b)2 now divide by 2: 150 = 100+b now subtract 100 50 = b You can always check your answer. For your case, 100 + 300/200 = 100 + 1.5 = 101.5 2x101.5 is not 300 To continue with your proposed solution, correct the distribution of the 2. 300 = (100+b)2 300 = 100(2) + b...

Consumers Math
divide the $80 by 6 to see how much each oil change costs with a coupon. So, you want to find out what percentage the discount is of the retail price of $15.95. So, subtract the coupon price from the retail price to get the savings, then divide that by the retail price. And, o...

physics
(a) just divide 790N by 1950 nails to get the force in N/nail (b) Now just change the number of nails to total area to get the pressure in N/m^2

Maths
She had 3/5 left, SO .6x = 21 x = 35

science
As I recall, we have the thermal expansion equation is dL = Lα dT where α for steel is 13.0*10^-6 m/m /°K So, since we want the diameter of the hole to increase by 0.0003 cm, we want the circumference to increase by .0003pi = .0009425 cm = 9.425*10^-6 m So, now w...

math - PS
sorry - forgot to eliminate my first line of thought; skip that stuff about |z| and |w|. There's probably a nice complex-number way to do this, but this was my first approach.

math
In other words, the two vectors are perpendicular If the two magnitudes are equal, then assuming that |z| >= |w| |z| = √(a^2+b^2) |w| = √(c^2+d^2) z+w = (a+c)+(b+d)i z-w = (a-c)+(b-d)i √((a+c)^2+(b+d)^2) = √((a-c)^2+(b-d)^2) (a+c)^2+(b+d)^2 = (a-c)^2...

Math - PS
Well, my most obvious mistake was using 3 as the length, not 300 (cm).

Math
when the water has depth y cm, the width of the surface has width 25+(75/50)y cm So, at depth y, the area of the trapezoidal cross-section is 1/2 (25 + (75/50)y)(y) = 3/4 y^2 + 25/2 y cm^2 So, the volume is v = 9/4 y^2 + 75/2 y cm^3 So, we want dy/dt when y=25, and we know tha...

Math-Exponential Decay
if the half-life is n days, then the amount remaining after t days can be modeled by 58(1/2)^(t/n) So, to find n, we just have to solve 58(1/2)^(10/n) = 52 (1/2)^(10/n) = 52/58 = 0.8966 10/n = log(52/58)/log(1/2) 10/n = 0.1575 n = 63.5 So, the half-life is about 63.5 days

math
I assume the pool is rectangular, with width x and length y. So, if the deck has width w, 2(x+y) = 50 2(x+2w + y+2w) = 74 2(x+y)+2(4w) = 74 50+8w = 74 8w = 24 w = 3

maths
to solve algebraically, just solve 3x-6 = x^2-6x+8 x^2-9x+14 = 0 (x-7)(x+2) = 0 The graphical solution is at http://www.wolframalpha.com/input/?i=solve+x^2-6x%2B8+%3D+3x-6

Math
thank you

Math
Solve the following 2a(a squared+4a)

algebra
If you mean h(t) = s - 16t^2 then we need s so that s-16*9 = 0 s = 144 ft

Algebra
ummm. The scores. If there are 10 scores, the 80th percentile ends at the 8th score. That is 80% of the scores. Extra credit: what is "context"?

Algebra
sort the scores in order. Find the lowest score greater than 80% of them. That is the 80th percentile score.

math
(2a) / (2u)(2v) = 2/4 * a/uv = 1/2 a/uv So, #3.

Math
The function rule C= 10 n + 26 where n = number of people and c = cost of party. Show a table if 27,39 , & 43 people go. My answer is the following n 27 39 43 c 296 416 456

Math
Write a function rule for the following table. x 2 4 6 y 1 0 -1

Math
Is y= -3 x squared +x a quadratic function?

Math
thank you

Math
If you have the following points for X and Y what is the linear function rule? x = 4, 1 y = 2, -4 I think it is 1/2 x but I'm not sure if it is +6 or - 6

Math
Now way it can be y=8x+8. adding two even numbers always produces another even, and most of your y values are odd. Also, if a relation is linear, then equal changes in x will produce equal changes in y. Here, we have x changing by 1 between steps, yet y changes by 8,7,9,8 So, ...

Math
Using the table below is it a linear function? x -2, -1, 0, 1, 2 y -7, 1, 8, 17, 25 my answer is that it is a linear function rule: x = -1 y = -8,-9,-7, -8 I think the rule is y= 8 X+8

Math
It was what I was doing. Thank you

Math
Solve for 5 X 3 to the nth,. my answer is 15, 45, 135, 405

Math
Is the following sequence a arithmetic,geometric or neither? 1.6, .8, .4, .2 my answer is geometric

grammer
Have you seen my sister Karla around here today? Harriet couldn't study for her comma quiz, because she asked to open the door for the neighbor, whom the dog wouldn't leave alone in the backyard.

algebra
I assume you mean to let x represent the "second" angle. So, we have x+23 + x + 6x = 180 Now just solve for x. After that, I assume you are supposed to indicate the measure of each of the angles...

Aths
throw a tool away from the ship. Conservation of momentum will cause you to drift slowly toward the ship.

Math
the surface was 4 pi r^2 = 36pi Now, replace r with (3/2) r and the new surface area is 4pi(3/2 r)^2 = 4pi * 9/4 r^2 = 4pi r^2 (9/4) = 36pi(9/4) = 81pi Or, you could just solve for r and get that r increased from 3 to 9/2, so the area increased from 36pi to 81pi.

Math
for each year, just add 4.5 t

Calc
y' = -.15y dy/y = -.15 dt lny = -.15t+c y = ce^-.15t with y(0) = 3, c=3 with y(0) = 4, c=4 with c=3, 3e^-.15t = 1 e^-.15t = 1/3 -.15t = ln(1/3) t = ln(1/3)/-.15 t = 7.32 with c=4, t = 9.24 So, the patient gets the 3rd dose after 7.32+9.24 = 16.60 hours.

Calculus
Ok. The information for S allows us to determine p, since the distance SF equals the distance from S to the line x = -p. So, 2p+5 = 10 p = 5/2 The equation of the parabola is y^2 = 4(5/2)x = 10x y = √(10x) Now we have to look at T. The slope of the tangent to the curve a...

math
If Ann not buy pink, Tom not buy red.

Algebra
sort the values, then divide them into four equal parts. Pick the 1st and 3rd portions.

ALGEBRA
√b^4 = b^2 √25 = 5 so, you have √(b^4/25) = b^2/5 = 4 b^2 = 20 so, b = ±√20 Those are the only two real answers. If you want the other two answers, you have to consider that b^2/5 = -4 b^2 = -20 b = ±√20 i

Algebra
you are correct. An odd formula, as most such calculations are based on degrees Kelvin.

pre algebra
well, geez. You have the formula. Pick any two (x,y) pairs and plug them in: (3-0)/(2+1) = 1 You can see just by looking at the table that when x increases by 1, so does y.

pre algebra
What is the slope for the following data? X -1 0 1 2 Y 0 1 2 3 y2 - y1 ---------- x2 - x1 rise / run

Alegbra
just solve for t in (1/2)^(t/5730) = 0.75

alegbra
so, what's the formula relating distance to amplitude?

Math
correct

Calculus
well, for f(x) to be differentiable, f'(x) must be defined. Surely you can see that 9x / 2√(3x^2+2) is defined for all real x...

calculus
yes, sorry I only gave the volume of the paraboloid, and forgot to subtract the cylinder inside. Better go with MathMate's answer.

Algebra
total points scored: 22*88 = 1936 Now we add 5 scores, increasing the total by 3*92 + 2*89 = 454 So, the new average for 27 students is (1936+454)/(22+5) = 88.52

ALGEBRA
The sides are in the ratio 1:√3:2, so with the hypotenuse=20, we have 10:10√3:20, with the longer leg opposite the larger angle. Looks like 17.3 to me.

algebra
2+4i

algebra
2+√-16

math
When contesting an answer, it'd be nice if you showed your own steps. I assert that (6x - 3 + 2x/y) * 2xy = (6x)(2xy)-(3)(2xy)+(2x/y)(2xy) = 12x^2y - 6xy + 4x^2 Now, if you just want a single fraction, Only the 2x cancels in all terms in the numerator, and you have 6xy - 3...

math
6x - 3 + 2x/y

ALGEBRA
why not just say "x+1" instead of "x+4-3"? And if x>=45 works, why not x>=48? or x>=53? I still suspect a typo.

Math7 Am I right?
Looks ok to me.

Science/Math
I'd say either. If the object is a turkey, chances are it'll be obliterated. If it's a flying block of titanium, it's more likely to have its course altered.

math
totals are Px and Ny so, the average we want is (Px+Ny)/(P+N)

maths
(a) the -x^2 means it opens downward (b) set x=0 to get y-intercept Since y = (1-x)(x-3) the x-intercepts are easy to see. (c) as usual, the vertex is at x = -b/2a = 1. Find y(1).

calculus
The cylinder intersects the paraboloid at z=5. The volume inside the paraboloid is v = ∫[0,2π] ∫[0,2] ∫[0,9-r^2] r dz dr dθ = ∫[0,2π] ∫[0,2] r(9-r^2) dr dθ = ∫[0,2π] 14 dθ = 28π

Math - eh?
which two stacks?

Math (Calculus)
we've done several of these for you. Got any ideas on this one?

Algebra
2h16' = 34/15 hours 4h32' = 68/15 hours Suppose it takes t hours to do the job working together. If the apprentice takes x hours, then it takes Sumi 3/4 x hours. So, we know that 1/t = 1/x + 1/(3/4 x) Also, we are told that (34/15)(1/t) + (68/15)(1/(3/4 x)) = 1 solving...

math
yes: (3x+1)(9) = 27x+9

calculus-answer check
The chain rule gives 2[(3x^2+1)^3+1] * 3(3x^2+1)^2 * (6x) This is an 11th-degree polynomial, so I suspect your answer is wrong.

Math
s = rθ = 13(65 * pi/180) = 169/36 pi

Math
r = (a+b-c)/2 5 = (a+b-19)/2 a+b = 29 p = a+b+c = 19+29 = 48

Math
If there are x reserved seats, receipts were 1.50x + .05*25x = 2.75x Now, we want y reserved $1 seats to fetch the same money: 1.00y + .05(26x-y) = 2.75x y + 1.3x - .05y = 2.75x .95y = 1.45x y/x = 1.45/.95 = .29/.19 = 29/19 So, now we want y/26x = 29/494 The ratio of reserved ...

Physics
well, you have dx/dt = 10cos53.1° = 6 dy/dt = 10sin53.1° - 9.8t = 8-9.8t y = 23.5+8t-4.9t^2 y=0 when t=3.15 At t=3.15, dx/dt = 6 dy/dt = -22.87 so, the speed is √(6^2+22.87^2) = 23.64 m/s Given that, I expect you can do part (b).

Math
it appears to be a repeating decimal 0.676767... rounded after 8 decimal places.

calculus-answer check
that's the proper method. Using the product rule, y' = (2x+3)(x^2-2) + (x^2+3x)(2x) at x=-1, that's (-2+3)(1-2)+(1-3)(-2) = 3

Algebra
1/R = 1/12 - 1/30 1/R = 1/20 R = 20

Algebra
just plug it into the formula: 1/12 = 1/R1 + 1/R2 Unless you know R1, you can't figure R2. If the lamps are identical, then R1=R2=24

Math ~ Check Answers ~
answers don't tell us much without the questions. #5: slope = 1 y = x-4 #6: slope = 3 y = 3x-1

Algebra
It wasn't the root symbol (which you can copy and paste fro my posting), but the "x+4-3" expression. Why not just say "x+1"? I suspect that is not what you had in mind. Was it √(x+4)-3 or something else?

Algebra - typo?
we want √(x+4-3) >= 4 I suspect a typo due to the odd nature of the expression.

Algebra 1
#1 correct because 256-320 < 0 #2 ok #3 what? you have the answer: ±√(12/5) as a decimal, that's ±1.55 12/5 = 2.4 and √2.4 = 1.55 You got no calculator?

math
just plug in the numbers: 2#a = 2*2+a a#3 = 2a+3 so, now we have 4+a = 2a+3 a = 1

math
given the area, the radius is 2. So, the diameter is 4. Two glasses side by side have width 8. So, the box is 8x8x8. The area of a face is 64.

Calculus
y dy = e^x dx 1/2 y^2 = e^x + c if (0,4) is on the graph, then 8 = 1+c c = 7 1/2 y^2 = e^x + 7 Looks like D to me dP/dt = k(10-t)/∛t Looks like E to me If you must use 3 to indicate the root, why say sqrt? The sq clearly implies square root. Try 3root of cbrt.

math
I will assume that you know how to find the area of a circle. In this case, that will be π ft^2 I must also assume you haven't studied packing density of circles, so we'll say the centers of the circles lie on a square grid. That said, since each circle has diamet...

Math
Well, think about it. Suppose their budget was 50% of the available property value. They'd have to tax it at 50% Instead, their budget is 27000 out of an available 1173913. So, what % is that? 27000/1173913 = 0.023 or, 2.3%

math
OK. I have an idea, if you know the Pythagorean Theorem. Draw ABC with the base BC, and point A at the top. Now, the line AB is length 2√2 and angle B is 45°. Draw the altitude AD to the base BC. Now you have a right triangle BDA with hypotenuse 2√2. Its legs A...

math
Hmm. So, you haven't had calculus, trig, or much algebra. What have you studied to enable you to find the area of a triangle, given two sides and the included angle? What chapter of the text presents this problem? I'd love to help you solve it, but some context would b...

math
Use the law of cosines to find AC: 8+64-2*2√2*8/√2 72 - 32 AC = 2√10 Now you can use Heron's formula to get the area = 8

geometry
You may not have seen it like this, but A = C/π

algebra
-3° is 18° less than 15° At 3°/hr that will take 6 hours, and happen at 6 pm. midnight is 12 hours after noon, so the temperature then will be 15-3*12 = -21°C Note that since 6pm is halfway between noon and midnight, since the temperature dropped 18° by...

science - not brilliant
The greater minus the lesser is -39 - (-98) = -39+98 = 59°C

math - typo?
since the diagonals are equal, 2(5a+1) = 2(a+1) 10a+2 = 2a+2 a=0 I don't think so...

maths - oops
oops - heh heh 3w = 12 w = 4

maths
length+width=9, so w + 2w-3 = 9 3w = 6 w = 2

math
r = 6w+1, so since r+w=50, 6w+1 + w=50 7w = 49 w = 7 r = 43

Math
the circumference is 20pi meters. So, the linear velocity is 60pi m/min. angular velocity is 2pi radians per revolution, so 6pi radians/min you know the circumference. Divide that by 8 to get the distance between seats.

new neutrich high school
depends -- do you want to know how many calories are burned as time passes, or do you want to know how long it takes to burn a calorie?

algebra
(f*g)(x) = f(x)*g(x) = (2x^2+7)(x-6) So, now just plug in x=1

Algebra
assuming you want to find the value(s) of s that make the equation true, place everything over the common denominator of (s^2-1) and clear fractions. Note that s=±1 are excluded, because that would involve division by zero. 3(s+1) + (s^2-1) = 12 s^2+3s-10 = 0 and I gues...

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