Friday

August 1, 2014

August 1, 2014

Total # Posts: 24,064

**geometry**

h/19 = tan52°

**geometry**

you have a right triangle, with vertical leg = 480 horizontal leg = 340 so, the angle θ from the horizontal base is tanθ = 480/340

**Science**

A skydiver prepares to jump out of a plane. Explain how gravity and air resistance will affect the motion of the skydiver before and after he or she opens the parachute.

**Science**

Use Newton's 1st law of motion to explain how wearing a seat belt in a moving car could help prevent injury.

**math**

a circle with center at (h,k) with radius r is (x-h)^2 + (y-k)^2 = r^2 Now just read off the values from your equation.

**Math**

you want to get m by itself. First, get everything with m on one side, and the rest on the other. Since both sides are equal, if you do the same thing on both sides, they remain equal. So, subtract 12 from both sides. That gives you 4m = 12 Now divide by 4 on both sides. That ...

**Calculus**

a = pi r^2 da/dt = 2pi r dr/dt Now plug in r and dr/dt to get da/dt.

**trigonomertry math**

we are in QIV, so sinA = -√8/3 Now just plug in the values for sinA and cosA to evaluate your expression.

**Calculus**

just find t where dd/dt = 0

**Calculus 1**

well, draw a diagram. If the width is x, then the length is 1000-2x. So, the area is a = x(1000-2x) = 1000x-2x^2 da/dx = 1000-4x da/dx=0 when x=250 As is usual, you will find that for maximum area, the fencing is divided equally among the widths and lengths. In this case, that...

**Calculus 1**

500x250

**Trig help**

3sinθ = sinθ - 1 I suspect a typo, but as things stand, 2sinθ = -1 sinθ = -1/2 since sin π/6 = 1/2, and sinθ < 0 in QII,QIV, we have θ = π+π/6 and 2π-π/6

**algebra**

No idea at all?

**math**

no; could be a rhombus, a kite, or even a trapezoid.

**mathhhh!**

wherever there is an x, make it a -2: f(-2) = (-2)^2 = (-2)(-2) = 4

**Science**

A person roller skates down a street heading West. What is true about friction in this case? the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward my answer is # 4

**Calculus**

secants connect two points on the graph. The slope of the secant is the average rate of change during that interval. The tangents are just secants where the interval has zero length -- their slopes are the instantaneous rates of change. The initial instantaneous rate is just t...

**Science**

thank you

**Science**

If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball? the choices are 0N 3N 6N 12N I think its 6N

**Algebra, math,**

a^6-b^6 = (a^2)^3 - (b^2)^3 = (a^2-b^2)((a^2)^2+(a^2)(b^2)+(b^2)^2) = (a-b)(a+b)(a^4+a^2b^2+b^4) now do the division and you are left with (a-b)(a+b) = a^2-b^2

**Algebra, math,**

since time = distance/speed, 700/(120-x) = 720/(120+x)+2 x = 20

**Math**

try some grouping: c^2(a-b) - a^2(a+b) + b^2(a+1) That pesky 1 at the end makes me think there's a typo. All the terms are degree 3 except that lone b^2. I suspect there may also be a sign mixed up somewhere as well. Are you sure that's the way it is?

**Science**

thank you

**Science**

A 2,500 kg car moves at 15 m/s squared, 15 m/s squared is the ? a-acceleration b- force c- velocity d-speed My answer is speed

**maths**

x = 21/(x-4) just by inspection, since the factors of 21 are 3 and 7, with one 4 less than the other, that's what I'd expect for roots of the equation. x(x-4) = 21 x^2-4x = 21 x^2-4x+4 = 21+4 (x-2)^2 = 25 x-2 = ±5 x = 2±5 That is, 7 or -3 We can't use...

**maths**

you can read the x-intercepts right off the original equation once you expand it to the desired form, the y-intercept is just the value of c. The vertex (turning point) is midway between the x-intercepts. Since the coefficient of x^2 is positive, the parabola opens upward.

**maths**

just solve for t in 520-5t^2 = 0

**Math**

I don't think this is determined. Take a look at http://mathcentral.uregina.ca/QQ/database/QQ.09.07/h/amanda1.html and you can see that depending on how you divide the diagonals, the median can be a variety of lengths.

**math**

correct until the last line. 7x+5(x+30) = 7*75 + 5*105 = 525+525 = $10.50

**Algebra 1**

If the old cloth had side s, the new cloth satisfies (s-2)(s+2) = 780 26x30

**Math**

the solutions are x = (3±√13)/2 pick the values close to those.

**Physics**

and she moves away from him at 3/4 his speed.

**Calculus- answer check**

Since R"=0 at t=2 and t=4, I see two inflection points. R'=0 at t=1 and t=4. Since R' and R" are both zero at t=4 (because of the multiple root there), there is no max/min at t=4. At R"(1)>0, so that's a local minimum. Not sure about the false sig...

**Math**

Looks to me like you have a typo. I get 1,11,21,1211,111221,312211,13112221,... or even 1,11,21,1211,3112,211213,312213,...

**Algebra 1--Please, help me!**

well, shoot. How do you graph any function? You pick some values for x, compute the value for y, and plot some points. Then draw a curve through the points. For y = 200/x + 5, start with x=1 and figure a few points. x y 1 205 2 105 3 71.7 4 55 and so on.

**algebra1**

I get C

**Geometry**

The volume of clay is for a cylinder of radius r is pi r^2(0.75) + pi(r^2-(r-.4)^2)h = 206 Since we have r=4.5, h = 14.6 cm The base is easy, and just subtract that from 206 to get the lateral volume. The lateral surface is just 2pi r h

**Algebra 2**

cos(360-x) = cos(x) so, same as cos 60°

**Math**

for y = a cos(kx) period = 2pi/k amplitude = a

**Algebra**

y^2/9 - x^2/16 = 1 so, what are the foci of y^2/a^2 - x^2/b^2 = 1?

**math Question**

(1-3^10)/(1-3) = 29524

**Algebra**

x^2 = 4py where p = -4 So, ...

**Please help w/ Algebra**

because the perimeter is 56, 2w + 2l = 56 l + w = 28 l = 28-w

**Please help w/ Algebra**

If the field has width w, then the length is 28-w. (w-4)(28-w-4) = 91 w^2-28w+187 = 0 w = 11 The field is 11x17 The smaller area is 7x13 = 91

**math Question**

40/160 = r^2, so r=±1/2

**Science**

A person roller skates down a street heading West. What is true about friction in this case? the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward my answer is # 4

**algebra 2**

#1 ok #2 is 80 or -80 b? #3 is a: P(2,3,4,5,6) = 5/6

**Science**

If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball? the choices are 0N 3N 6N 12N I think its 6N

**Algebra 2**

If xy is constant, it's inverse If x/y is constant, it's direct Looks like (b) to me (c) is a bogus answer in any case.

**math**

you are correct.

**math!**

15*12 = 180 330-180 = 150 150/14 = 10 remainder 10

**Multiple Choice**

correct

**Science**

the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward

**Science**

A person roller skates down a street heading West. What is true about friction in this case?

**Science**

answers to chose from are 0N, 3N, 6N, 12N

**Science**

If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball?

**math**

1260(1-cos20°)

**Trig**

x^2+11^2 = 24^2 now just solve for x

**maths**

1260(sin30°)

**math**

depends. Is the same formula used for tv's and computers? If so, retail = 2*wholesale-75 wholesale = (retail+75)/2 so, plug in a retail price of $550

**maths**

a^-3 = 1/a^3 c^-1 = 1/c, so 1/(c^-1) = c^1 and we have bc/a^3

**math**

4 times the diameter, 16 times the area

**Precal/trig**

cos2a = 1 - 2sin^2(a) = 1 - 2*9/25 ... in this case, it doesn't really matter which quadrant a is in, as sin^2 is always positive. extra credit: which quadrant is 2a in?

**math help !**

Looks like D to me For #2, always check to see how much y changes when x changes by a fixed amount. That will give the slope of the line (the coefficient of the x term). Here, when x changes by +2, y changes by -1. So, the slope will be -1/2 and the function rule will look lik...

**math**

Better check B. It's the differences that are constant, not the ratios. A gives an exponential function. Consider y = 2^x when x grows by 1, y doubles. But, if y = mx+b (a linear function) when x grows by 1, y grows by m, and the difference is constant over equal intervals.

**Calculus**

you want to find c. So, since y(1) = 4, plug it in -1/(1^3+c) = 4 -1/4 = 1+c c = -5/4 Now the particular solution is y = -1/(x^3 - 5/4)

**Calculus**

You wan to find c, so plug in the point (-4,-1) which is on this particular solution curve: (-3*16)/(2+4+c) = -1 The way the function is worded makes me suspect a typo. Fix that, and find c for a particular solution.

**Calculus**

or, 2,000,000 = 10,000,000/5, so log 10^7 - log5 = 7-.699 = 6.301

**Calculus**

log2000000 = log 2 + log 10^6 = 6.301

**help please**

intraocular fluid is the answer I think

**derivative**

you can check your results at wolframalpha.com Just type "derivative" or "2nd derivative" and your function. Check to be sure it interprets your input as you intended. Parentheses are your friend. For your function, you correctly extracted the 9/e constant,...

**Calculus**

log(1000000x^19) = log(10^6)+log(x^19) = 6 + 19logx assuming logs base 10 :-)

**Math help**

Assuming ã means √, √338-√200+√162 = √169√2 - √100√2 + √81√2 = 13√2-10√2+9√2 = 12√2 Do the other in the same way: extract perfect roots, and combine the other factors under a single √

**Math help**

#1 -4√2+6√72-√32 = -4√2 + 6√36√2 - √16√2 = -4√2 + 36√2 - 4√2 = 28√2 #2 ok #3 12√13-74√2 remember that √8 = 2√2 #4 ok

**math**

correct except for the inconsistent capitalization

**math**

4! The fact that you are asking this question indicates that you are studying permutations. Surely it was explained in the text.

**math**

view it at wolframalpha.com This site will show you how to graph any function you care to enter. Play around some. http://www.wolframalpha.com/input/?i=1%2F3|x|-2+ Be sure to check to see how it interprets your input. It is pretty strict about using parentheses to alter the or...

**math**

If y = -2x^2 + 3, then just use the values of x and calculate the values of y: x y -3 -2(9)+3 = -15 -2 -2(4)+3 = -5 -1 -2(1)+3 = 1 0 -2(0)+3 = 3 1 1 2 -5 3 -15 Plot those points and sketch a smooth curve through them. Your graph should look like the one given by wolframalpha: ...

**Mathematics**

since the circumference of the ball is 2pi*11.5 = 72.26 cm, divide that into 2800cm to see how many times it rolls.

**Algebra**

add 5 to get the next terms.

**algebra - typo?**

I suspect a typo, since log3(√10+1)+log3(√10+1) = log3(10-1) = log3(9) = 2 the log7 of powers of 2 is not amenable to simplification. Is there a typo? At the very least, the parentheses are not balanced.

**math**

12 = 2^2 * 3 15 = 3*5 18 = 2*3^2 The smallest number which is a multiple of all of those must contain the highest power of each of the listed primes. So, that will be 2^2 * 3^2 * 5 = 180 But, we also want our number to be a perfect square, so we need to have 5^2 in the product...

**Calculus**

Judging from the graph at http://www.wolframalpha.com/input/?i=[3x^13]e^%28%E2%88%927x%29+for+x%3D0..3 I'd say it is concave down in that interval. In fact, since f"(x) = 3x^11 e^-7x (49x^2-182x+156) if the roots are where you say they are, then since the quadratic fa...

**Calculus**

concave down where f" < 0 better review your text, where it is surely explained and illustrated. f" < 0 means that the slope is decreasing. So, f is either rising either rising more slowly or falling more quickly. Consider a parabola which opens downward.

**geometry**

gain of what? perimeter will gain 10% area will grow by a factor of 1.1^2 = 1.21, or 21%

**average and instantaneous rate of change**

average is measured over some finite time interval. Instantaneous is not. It is the limit of the average rate, as the measured interval decreases to zero.

**algerbra**

Ethan donates 1/25 of which money? His earnings, the total earned, the total donated, or what?

**math**

you can convert the hours to minutes 14 X 60 = 840 then add the 3 minutes 840 +3 =- 843 then divide 843/3 = 281 then divide by 60 = 4 hours and 41 minutes

**Math**

Simplify the expression 14 to the minus 4 power

**Math**

Simplify the expression (-8x) times 3x squared

**Math homework help**

AG CE FH

**Math**

5+3√2

**Calculus**

the 3.02375 is correct, but you lost a factor of 10^-8 So, what you really have is .03 micrograms

**Math - Bazinga!**

you gotta be kidding. I suggest you pick out one or two of the types of questions that bother you, post your solutions, and we can check and/or critique them.

**Algebra**

.85^4

**Calc Help Please Again!**

the volume is just a stack of thin discs, of thickness dx, and radius y So, the volume is the integral of pi * y^2 dx = pi*(e^2x + 8e^x + 16) all pretty straightforward. C'mon back if you get stuck, and show where.

**Algebra 1**

first, draw the asymptotes. Then pick a few values of x near the vertical asymptotes, so you get a feel for how y behaves in that region. Then pick a few more values a little farther away, and draw the curve, keeping in mind that it will approach the horizontal asymptote on th...

**trigonometry**

tanθ=1/7 means sinθ=1/√50 cos 2θ = 1-2sin^2θ = 1-1/25 = 24/25 tanØ=1/3 means sinØ=1/√10 and cosØ=3/√10 sin2Ø = 2sinØcosØ = 3/5 so, cos2Ø = 4/5 sin4Ø = 2sin2Øcos2Ø = 24/25

**algebra**

not geometric. The ratio between terms changes. What you have is a modified Fibonacci sequence, where for n>=2, T(n+1) = 2*(T(n-1)+T(n))

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