Wednesday

February 22, 2017
Total # Posts: 48,712

**Science**

50m/2.8s = 50/2.8 m/s = ...

*January 11, 2017*

**Calculus Please Help**

Assuming the x values for the table are 1,2,3,4 then d/dx g(f(2x)) = g'(f(2x)) * f'(2x) * 2 = g'(f(2)) * f'(2) * 2 = g'(1) * 2 * 2 = 5*2*2 = 20 consider something like y = e^sin(2x) y'(x) = e^sin(2x) * cos(2x) * 2

*January 11, 2017*

**Calculus**

looks good to me

*January 11, 2017*

**Calculus**

Hmmm. h is constant at 12, so V = ?r^2h = 12?r^2 dV = 24?r dr ...

*January 11, 2017*

**Math parallel lines and angles**

no diagrams visible here. Just recall what you know about alternate angles and adjacent angles of transversals.

*January 11, 2017*

**Angle Math Help!**

well, you could always consider the 5-12-13 right triangle.

*January 11, 2017*

**Geometry**

I don't see how YO can divide the square. It just goes from a side to the center.

*January 11, 2017*

**Math Calc**

Hmmm 3.14*4.2^2 * 12.2 = 665.75 other than that, your logic is sound. Also, note that the error using 4.0-0.2 in for the low-side value differs by a smaller amount.

*January 11, 2017*

**Math Calc**

if 3.8 <= r <= 4.2, ?*3.8^2*12 <= v <= ?*4.2^2*12 544.32 <= v <= 665.01 ...

*January 11, 2017*

**math algebra**

15.99 + 0.93m = 259.65

*January 11, 2017*

**Calculus**

see the further discussion on your earlier post.

*January 11, 2017*

**Calculus**

That is because x=0 is the single point where f'(x) = 0 the number zero is a single choice, not an absence of choices! The answer is 1 There is 1 (one) point on the interval [-1,1] where f(1)-f(-1) ------------ = 0 1 - (-1) That point is at x=0. Just take a deep breath and...

*January 11, 2017*

**Calculus**

Excuse me? Did you look at the graph? Did you actually read what I wrote? I don't mind helping you arrive at a solution, but I do expect you to actually read it, rather than just hold out your hand and say "gimme the answer." In fact, I did give you the answer.

*January 11, 2017*

**Calculus**

absolute value problems can get tricky, because the functions are not differentiable at any cusps. However, since (x^2-9)(x^2+1) is negative on [-1,1], f(x) = -(x^2-9)(x^2+1) This is a nice smooth polynomial, so it satisfies the requirements of the MVT on [-1,1]. Now take a ...

*January 11, 2017*

**Calculus**

v(t) = 0 at 0,?,2? If you exclude the endpoints of the interval, your answer is correct. But, we are working with the closed interval, including the endpoints. So, there are 3 points where v(t) = 0. Better review interval notation.

*January 11, 2017*

**Calculus**

v(x) = -sin(x) e^cos(x) since e^cos(x) is never zero, how many times in sin(x) = 0 in the interval? Your answer is correct on the interval (0,2?), but not on [0,2?]

*January 11, 2017*

**Vectors**

This is discussed here: http://math.stackexchange.com/questions/1408917/finding-vector-form-of-an-angle-bisector-in-a-triangle

*January 11, 2017*

**Maths**

Using x and y for syntactical reasons, See http://www.wolframalpha.com/input/?i=%7B%7B7,9%7D,%7B5,7%7D%7D*%7B%7Bx%7D,%7By%7D%7D+%3D+%7B%7B3%7D,%7B1%7D%7D

*January 11, 2017*

**Calculus**

try (lim x^3) * (lim sin(1/x)) x^3 -> 0 |sin(1/x)| <= 1

*January 11, 2017*

**Maths**

1 degree of latitude is about 111 km. So, 800 km/hr ? 800/111 = 7.2°/hr so, ...

*January 11, 2017*

**Maths**

Check the diagram. The radius of the latitude at angle ? is r*cos?. Since speed is proportional to the radius of rotation, if B is at angle ?, r cos22° = 2r cos?

*January 11, 2017*

**math;););)**

so, do you know the rotation matrix?

*January 11, 2017*

**Math;);)**

Actually, it's even better than that: |u + v|^2 ? |u|^2 + |v|^2 ? (|u|+|v|)^2

*January 11, 2017*

**Calculus**

since when is x^2/x^2 = 2? 10/10 = 1 z^3/z^3 = 1 don't forget your Algebra I now that you're taking calculus. Using the usual method, divide top and bottom by x^2. That gives you (1 + 2/x^2)/(1 - 36/x^2) as x^2 gets huge, 1/x^2 -> 0 and the fraction becomes 1/1 NOT 2!!

*January 11, 2017*

**Calculus**

as x gets huge, the 2 and the 36 become insignificant: y -> x^2/x^2

*January 11, 2017*

**Physics**

40 S = <0,-40> 70 N30ºW = <-35,60.6> add them up, then convert back to compass directions.

*January 11, 2017*

**Math**

1700 * .96*9

*January 10, 2017*

**calculus**

a = t^2-5t+3 v = 1/3 t^3 - 5/2 t^2 + 3t + C1 s = 1/12 t^4 - 5/6 t^3 + 3/2 t^2 + C1*t + C2 Now use the conditions to solve for C1 and C2.

*January 10, 2017*

**pre-Calculus**

a: odd b: even c: unknown check by using the fact that odd: f(-x) = -f(x) even: f(-x) = f(x)

*January 10, 2017*

**Math**

100/(b+24)

*January 10, 2017*

**Trig**

If the base is 2x, then 12.5/x = tan 55° The area is just 12.5x

*January 10, 2017*

**Math**

-.25x^2+5.5x-5.25 = -1/4 (x^2-22x) - 21/4 = -1/4 (x^2-22x+121) - 21/4 + 121/4 = -1/4 (x-11)^2 + 25

*January 10, 2017*

**Math**

8C4

*January 10, 2017*

**Math**

w(w+5) = 50 Now, which factors of 50 differ by 5?

*January 10, 2017*

**Algebra**

4a-2b+c = 5/2 c = 3/2 16a+4b+c = -121/2 F(x) = -5/2 x^2 - 11/2 x + 3/2

*January 10, 2017*

**Math**

just plug in the numbers. What do you get?

*January 10, 2017*

**Math**

there are only a few factors of 32, all of them powers of 2. It must have 2 digits, so there is only one that fits.

*January 10, 2017*

**Math**

well, they surely end in 3, so look up a list of primes and add them up.

*January 10, 2017*

**Trig/PreCalc**

as t changes from 0 to 1, x changes by -7 y changes by -6 x = 5-7t y = 2-6t

*January 10, 2017*

**Trig/PreCalc**

t = y-2 x = 5-3t = 5-3(y-2) It is clearly a line.

*January 10, 2017*

**Trig/PreCalc**

If we label the points A,B,C, then AB=?84 BC=?41 AC=?85 85 = 84+41-2?84?41 cosB Now you can use law of sine or cosine for one other angle, and then the angles sum to 180.

*January 10, 2017*

**Math**

A = 2/3 b b = 3/4 c a+b+c = 8200 Now just solve for c.

*January 10, 2017*

**Chemistry**

For the following reactions, determine the equilibrium constant equation. 1) CO2(g) + H2(g) CO(g) + H2O(g) 2) 2NO(g) + 2H2(g) N2(g) + 2H2O(g) 3) Cu(s) + 2Ag+(g) Cu2+(g) + 2Ag(s) 4) H2(g) + I2(g) 2HI(g)

*January 10, 2017*

**Math**

if the dimensions are x,y,z then there are 3 pairs of parallel faces. The area is thus 2xy + 2xz + 2yz Now just plug in your numbers.

*January 10, 2017*

**algebra**

what two factors of 32 differ by 4? y = (x-8)(x+4) the discriminant is b^2-4ac = 16+128 = 144

*January 10, 2017*

**Algebra**

use what you know about arithmetic sequences, in this case a = 1 d = 2 n = (49-1)/2 + 1 = 25 S25 = 25/2 (1+49)

*January 10, 2017*

**algebra**

you know that the axis of symmetry is at x = -b/2a = 4/2 = 2 Symmetry means that the two roots are equally spaced on either side of the axis.

*January 10, 2017*

**algebra**

4*3*2 = 24 5184/24 = 216 = 6^3 ... Or, more usually you will be asked to solve 4x * 3x * 2x * 5184

*January 10, 2017*

**algebra**

2b+2 = 4b-46

*January 10, 2017*

**Graphing in the Coordinate Plane Unit Test**

if you cannot plug in the values and evaluate the expression, you are in deep trouble. For example, is (5,3) a solution? -4(5)-9 = -29 Nope, not equal to 3.

*January 10, 2017*

**trig**

duplicate posts are a waste of time, both yours and ours...

*January 10, 2017*

**math**

draw a diagram review your basic trig functions. (h-5)/90 = tan 81°

*January 10, 2017*

**Math**

all correct.

*January 10, 2017*

**geometry**

Totally!

*January 10, 2017*

**Math grade 6, quadrilateral logic**

Hmmm. I thought a trapezoid was a quadrilateral with only one pair of parallel sides. I guess it depends on who is doing the defining...

*January 10, 2017*

**Math**

see your previous post.

*January 10, 2017*

**algebra 2**

What is the s9mplermform of the radical expression? sqrt36g^6 my answer is 6lg^3l

*January 10, 2017*

**Algebra2**

?5 * 3?5 = ?5*?5 * 3 = ...

*January 10, 2017*

**Algebra2**

Find the product sqrt 5 times 3sqrt5

*January 10, 2017*

**math**

Looks like C to me. Draw a line and locate points P and Q. Now, note that R can be on either side of P.

*January 10, 2017*

**geometry**

see http://www.ask-math.com/constructing-triangles.html

*January 10, 2017*

**Math science etc**

google is your friend: http://www.ask-math.com/constructing-triangles.html

*January 10, 2017*

**9th grade algebra (recursive formula)**

You're welcome. As for the notation, I'm not sure it's "correct" or standard. I just thought of using it since making subscripts is a pain, and the parentheses sometimes get confused with function notation. You will also see An, An+1 (ambiguous: cf. (An)+...

*January 10, 2017*

**9th grade algebra (recursive formula)**

a<18> = a<1> + 17*200 = 3362 So, a<1> = -38 similarly, a<21> = a<1> + 20*0.6 = -1.4 now again, just solve for a<1> a<n> = a + (n-1)d

*January 10, 2017*

**math**

12c+b

*January 9, 2017*

**Math**

hint: a and w are times, and add to 12.

*January 9, 2017*

**Math**

You have a slight(!) error: R = 100/?q * q = 100?q Profit = R-2q-1200 = 100?q - 2q - 1200 maximum profit where dP/dq = 0 50/?q - 2 = 0 50 = 2?q q = 625 since P = R-C, dP/dq = 0 when dR/dq = dC/dq The price is 100*25 = 2500

*January 9, 2017*

**Trigonometry**

Just recall that C = 2pi * r

*January 9, 2017*

**Math**

the sides are equal, so 4a = 3b 4a = a+b+c c = 3a-b, so 4(3a-b) = 3b 12a-4b = 3b 12a = 7b subtracting, 8a = 4b or 4a = 2b But, 4a = 3b, so 2b = 3b b=0 You only supplied two equations for three variables, and 0 is not a likely solution. Check for typos and try again.

*January 9, 2017*

**math**

sin(theta) = y/r just to remind you, r^2 = x^2+y^2

*January 9, 2017*

**algebra sir reiny sir steve&bob damon help**

By inspection, it should be clear that 3*3^2 = 3^3 There is another solution, at about x = 0.4844 but you won't arrive at it algebraically. You can tell that 3 * 1/4 ? ?(1/2) 0.7500 ? 0.7071

*January 9, 2017*

**MATHS**

consult your trig text, or just google its images. sheesh ...

*January 9, 2017*

**Math**

since he wants 4 times the recipe, the cups turn to quarts: He will need 1.25 qt

*January 9, 2017*

**Geometry**

since BD bisects ABC, mABD = mDBC, and they add up to mABC: 9x = 2(4x+38)

*January 9, 2017*

**MATH**

rats: ?3y y^6 z -------------- x

*January 9, 2017*

**MATH**

?3 = 3^.5 z^0 = 1 So, we can write this as x^4 y^.5 z 3^.5 ------------------- = (y^6.5 3^.5/x) = ?(3y)y^6/x y^-6 x^5

*January 9, 2017*

**math**

3.5mi/22.25min = 0.157 mi/min

*January 9, 2017*

**Math**

84.06 m 8406 cm

*January 9, 2017*

**math**

48*8 + 54*9 = ?

*January 9, 2017*

**Math**

320rs / (5rs/m^2) = 64 m^2

*January 9, 2017*

**math**

well, he made 5.18-2.32 = $2.86 on each shirt, so ...

*January 9, 2017*

**Math**

the side length of the field is 32000/16 / 4 = 500 meters So, now you can get the area, and thus the cost.

*January 9, 2017*

**Algebra**

and did you check your answer? 2*4+2 = 10 4-3*2 = -2 yes, it works.

*January 9, 2017*

**Math**

huh? what are x and y?

*January 9, 2017*

**AP Calculus**

It depends on how far away B is when sighted. If it is k km north and west, then the distance z between the ships after t hours is z^2 = (k-3t)^2 + (k-8t)^2 = 73t^2-22kt+k^2 dz/dt = (73t - 11k)/?(73t^2-22kt+k^2) dz/dt=0 when t = 11k/73 so, the minimum distance is z = 5k/?73

*January 9, 2017*

**Pre-Calculus**

x(160-2x)

*January 8, 2017*

**Math**

as always, for y=ax^2+bx+c, the vertex is at x = -b/2a = -3 f(-3) = -(b^2-4ac)/(4a) = -4

*January 8, 2017*

**calculus**

You have to be kidding!! The entire area is only growing at 3 in^2/s. You need to learn to do a sanity check on any answer you get, especially in a new situation. Using the given equation and numbers, we have 3 = 2?*10 dr/dt dr/dt = 3/(20?) = 0.0477 in/s Your answer is 60?. ...

*January 8, 2017*

**calculus**

well, a = ?r^2 da/dt = 2?r dr/dt ...

*January 8, 2017*

**MATH**

well, the height y at time t is y = 33 + 64t - 16t^2 So, solve for t when y=48. The max height is of course, when t = 64/32 = 2. I expect you can determine the range... (restrict it to the domain involved.)

*January 8, 2017*

**Math**

There are 2^3-1 = 7 ways to choose at least one stamp.

*January 8, 2017*

**Calculus**

y = 1-x z = xy = x(1-x) now just use what you know about parabolas. No calculus needed here. Of course, you can verify that the max occurs at the vertex...

*January 8, 2017*

**calculus**

I'll do (b) to show the way. Of course, you probably already know the way... Assuming you meant f(x) = x^3+x-4, f(-2) = -14 f(3) = 26 slope of secant is 40/5 = 8 f' = 3x^2+1 3x^2+1 = 8 3x^2 = 7 ... clearly, ?(7/3) is in [-2,3]

*January 8, 2017*

**Math**

4" is 1/3 foot. So, (h - 1/3)^2 + 4^2 = h^2 Damon is correct. 24'2"

*January 8, 2017*

**math**

Let the plane be x west, and the jet be y south of St. Louis. Draw a diagram. Then the distance z between the two aircraft is z^2 = x^2+y^2 At the moment in question, 300^2 = 100^2+y^2 y = 100?8 z dz/dt = x dx/dt + y dy/dt 300 dz/dt = 100(-500) + 100?8 (-600) dz/dt ? -732 mi/hr

*January 8, 2017*

**calculus**

f(1) = -3 f(2) = 12f(1) = -36 ... Clearly, f(n+1) = -3*12^n

*January 8, 2017*

**math**

Draw a diagram. If the man is x feet from the tower, and his shadow is s ft long, then using similar triangles, s/6 = (x+s)/40 s = 3/17 x ds/dt = 3/17 dx/dt ...

*January 8, 2017*