Sunday

December 4, 2016
Total # Posts: 46,790

**math**

43C9 = ?

*November 19, 2016*

**math - business**

highest profit is at the vertex, when x = -b/2a = 4/.01 = 400 P(400) = 600

*November 19, 2016*

**algebra/pre-calc - please help**

If we use x as the number of days since the start of the year, build each piece with a y=mx+b section, where the price starts a t b and the line has slope m ($/day) January is y = 10 + 2/31 x February is 12 - 3/28 (x-31)

*November 19, 2016*

**blah blah blah**

a+b=15 10b+a = 10a+b - 27 69 = 96-27

*November 19, 2016*

**math**

what, you can't plug in h=1 or h=6? and online you write 5e^(-0.4h)

*November 19, 2016*

**algebra**

.40*.80 = .32 so, .20x = .18 x = .9 so, win 90% of the remaining games.

*November 19, 2016*

**Algebra 2**

well the slope is -3/4, and the point slope is y-k = m(x-h) so plug in your numbers. It does not matter which point you choose for (h,k).

*November 19, 2016*

**algebra 2**

usually a complex number is written a+bi, and coefficients come before variables. I know it is tempting to put the ?5 last so it does not get confused with following numbers, but that's just orthography. here, a is zero, so just bi: 6?5 x^4 i

*November 19, 2016*

**algebra 2**

me too Usually the i comes last, though.

*November 19, 2016*

**math**

I recall such rates in about 1964, but it was, of course, compound interest.

*November 19, 2016*

**Pre-calculus**

This one is easier if you work on the right side. (sin(x-y)/cos(x-y)) / (sin(x+y)/cos(x+y)) (sinxcosy-cosxsiny)/(cosxcosy+sinxsiny) ------------------------------------- (sinxcosy+cosxsiny)/(cosxcosy-sinxsiny) Expand those products, and you will be able to factor out some (sin...

*November 19, 2016*

**Physics**

none, except against air resistance. For a given force at takeoff, the mass affects the acceleration.

*November 19, 2016*

**Math**

Think about y=x^2 x can be either plus or minus and produce the same y value. Sp, as y grows on one side of the axis, it also grows on the other side. Plot a few points.

*November 19, 2016*

**java program**

you mean display the code? Surely the payroll system displays its own information.

*November 19, 2016*

**Algebra**

well, 3n^2+5n-100 = (3n+20)(n-5)

*November 19, 2016*

**maths**

AC = 1/2 AB PC = 1/2 AC = 1/4 AB

*November 19, 2016*

**Math**

81 = 3*27 so, the number is 4*27

*November 19, 2016*

**math**

if the scale factor is s, then P2/P1 = s A2/A1 = s^2

*November 19, 2016*

**Maths**

You can start here. Once you know the side length of the triangle, you can get its area. https://owlcation.com/stem/Inscribed-Circles-and-Equilateral-Triangles-7-Hard-Geometry-Problems-and-Solutions

*November 19, 2016*

**math**

If the %ages are based on the gross, then she saves (628-148.90-628(.045+.08))*.10 = $40.06 If they are based on after-tax income, then she saves (628-148.90)(1-(.045+.08)))*.10 = $41.92

*November 18, 2016*

**Precalculus**

D: all reals R: all reals > 0

*November 18, 2016*

**chemistry**

f" = -36sin(6x) f' = 6cos(6x)+c f'(0) = 6+c = -5, so c = -11 f' = 6cos(6x)-11 f = sin(6x)-11x+c f(0) = c = -3 f = sin(6x)-11x-3 f(?/3) = sin(2?)-11(?/3)-3 = -11?/3 - 3

*November 18, 2016*

**Math**

boy, you don't give much away, do you? The average value is ?[a,b] f(x) dx ------------------ b-a So, what didn't work? ?[-1,2] 4x^3-3x^2 dx = x^4-x^3 [-1,2] = (16-8)-(1+1) = 6 6/3 = 2 So, where is f(x)=2? 4x^3-3x^2=2 x ? 1.137

*November 18, 2016*

**Math**

see the related questions below. Just use your function instead.

*November 18, 2016*

**English**

#1 means that you are in sustained flight higher than the clouds #2 implies that in a while you will come back down, as in "The cow jumped over the moon." #3 Lots of explanations online. You might start here: http://www.grammarbank.com/impersonal-pronouns.html

*November 18, 2016*

**Calc**

http://www.jiskha.com/display.cgi?id=1479256552

*November 18, 2016*

**Math help please**

yes

*November 18, 2016*

**Math help please**

geez -- impatient much?

*November 18, 2016*

**Math help please**

TeX is not much good here, as you can see.

*November 18, 2016*

**Math help please**

a pizza place charges $5 per pizza, with a $7 delivery fee. How much does a delivery order for x pizzas cost?

*November 18, 2016*

**math**

try just posting a problem without copying all the surrounding text, eh? Don't make us figure out the question as well as the answer. Clean it up and post it again. Maybe just one question. Learn from its solution and try more on your own.

*November 18, 2016*

**Math**

If the length is x, then 2(x + 2x-8) = 104

*November 18, 2016*

**Math**

since y=2x-5, 4x-(2x-5) = 7 Now solve for x, and then you get y.

*November 18, 2016*

**Maths**

The yacht should take a bearing of the harbour, and then sail on that heading. Not sure what 065T means, but I assume it's 65° clockwise from True North. If so, then the heading back to the harbour is found via Label the diagram as follows: H = harbour P = point of ...

*November 18, 2016*

**Physics**

conserve momentum: 3500(45) + 1600(-25) = (3500+1600)v

*November 18, 2016*

**Functions**

so, what is your work? Show how you did it.

*November 18, 2016*

**Functions**

Oh come on. Just plug in their definitions: g(x) = f2(x)-f3(x) = (1/8(x+16)^2-98)-(2x+24) = 1/8 x^2 + 2x - 90 f1(x)=0 is stupid, as it contributes nothing.

*November 18, 2016*

**Functions - huh?**

Determine an equation for this function WHICH function?

*November 18, 2016*

**Calculus**

the chain rule says that d/dx(fg) = f'g + fg' not f'*g'

*November 18, 2016*

**Calculus**

clearly, y(0) = 4 y'(0) = 0 So, a parabola with vertex there will work: y = 2x^2+4 or how about a cosine function? y = 4cos(x)

*November 18, 2016*

**math**

In standard form, x^2/9 + y^2/4 = 1 a = 3 b = 2 c = ?5 You are correct that the foci are at (±?5,0) The directrices are at x = ±a^2/c = ±9/?5

*November 18, 2016*

**math**

Clearly the distance z between the ships can be found using z^2 = (Ax-Bx)^2 + (Ay-By)^2 = (-t+20)^2 + (-2t+10)^2 = 5t^2 - 80t + 500 2z dz/dt = 10t-80 dz/dt = 0 when t=8. So, just evaluate z at t=8.

*November 18, 2016*

**Algebra**

#1 clearly A grows by 0.6 for each new term. suppose A(n) = 0.6(n-1) But, when n=0, A(0) = 0.3 so just add that at the start. A(n) = 0.6(n-1) + 0.3 #2 A(n) starts at 47 and drops by 15, so start with A(n) = 47-15(n-1) The (n-1) stuff pops up because the first term (n=1) has ...

*November 18, 2016*

**math**

oops. That gives the untranslated parameterization. You want to shift things, so x = sec(t)/3 - 2 y = 4tan(t) + 4 so that 9(x+2)^2 - (y-4)^2/16 = 1

*November 18, 2016*

**math**

you know that sec^2(t)-tan^2(t) = 1 so, let x = sec(t)/3 y = 4tan(t)

*November 18, 2016*

**Math**

just compare cost/volume

*November 18, 2016*

**Math**

a = pi r^2 da = 2pi r dr now just plug in your numbers.

*November 18, 2016*

**Calc**

Graph the function. The area is just a couple of triangles.

*November 18, 2016*

**Calculus**

sin^2(x^2) * 2x

*November 18, 2016*

**Mathematics**

"there" not "their" if the road (or walkway) has width w, then the length is 45-2w

*November 18, 2016*

**Calc**

f(3) = 27 f(0) = 0 so, the slope of the secant line is 27/3 = 9 So, you need 3c^2 = 9 c = ?3

*November 18, 2016*

**Algebra**

four times a number is 4w so, ...

*November 18, 2016*

**math**

There are clearly no real solutions, but you can factor it into (x^2-x+1)(x^2+x+1)(x^4-x^2+1) = 0 because x^8+x^4+1 = x^8+2x^4+1 - x^4 = (x^4+1)^2 - (x^2)^2 a difference of two squares Now you can find the roots of those quadratics

*November 18, 2016*

**math**

and inept at following instructions, it appears...

*November 18, 2016*

**Order MATH!**

2/3 = 0.66 7/10 = 0.70 now things should be clear.

*November 18, 2016*

**maths**

the area is just 1/2 ab the area is just 1/2 bc sin?

*November 18, 2016*

**maths**

(a) ? is easy, since the angles sum to 180° Then use law of sines to find b,c (b) this is a right triangle. a^2 = b^2+c^2 then just use the trig functions to get the other two angles. (c) use the law of cosines to get any or all of the angles. Or, having one, you can use ...

*November 18, 2016*

**maths**

find the reference angle in QI. only sin x is positive in QII. For example, cos x = ?2/2 x = 45° Since cos x < 0 in QII, that is the only solution. Work the others in like wise.

*November 18, 2016*

**Maths**

just list the terms. 6 is the last to appear.

*November 18, 2016*

**Maths**

Think of a rectangle. The maximal area is achieved when it is a square. Similarly for a rectangular prism, the maximum volume is when it is a cube. so, in this case, the sum is just 3?2001

*November 18, 2016*

**Geometry**

#4 Remember the 3-4-5 right triangle. This is just double that. You got #1 right. How could you not be sure on #4?

*November 18, 2016*

**Geometry**

#1 ok #2 the sides are 26/?2 = 13?2 If the sides of a square are 1, the diagonal is not 2. #2 In such a triangle, the sides are 1,?3,2 Now multiply everything by 8. (c) is wrong.

*November 18, 2016*

**math**

and how did you arrive at that figure? Take a piece of graph paper and draw a 6x8 rectangle on it. You really think the diagonal is 48? Think of the Pythagorean Theorem here.

*November 18, 2016*

**Math**

she got 1/6 wrong. so, ...

*November 18, 2016*

**Calc**

I assume you mean x^(2/5) since f' = 2/5 x^(-3/5) it is undefined at x=0

*November 17, 2016*

**Calculus**

are they the same?

*November 17, 2016*

**Calculus**

a = ?(x/2?)^2 + (14-x)/6 * (14-x)/3 P = (12+x)(27-3x) - (4x)

*November 17, 2016*

**calculus**

11,33,55,77,99,121,319,517,539,...,979

*November 17, 2016*

**Math**

see related questions below

*November 17, 2016*

**mathematics**

no idea. Where is D?

*November 17, 2016*

**Math algebra**

(20+2w)(30+2w) = 936 w = 3

*November 17, 2016*

**Algebra**

you want x^2+y^2+6y+5 = x^2+y^2-2x-8 6y+5 = -2x-8 y = -(2x+13)/6 Now use that to find x: x^2 + (-(2x+13)/6)^2 - 2x - 8 = 0 40x^2 - 20x - 119 = 0 x = [5±9?15]/20 y = -3/20 (15±?15) http://www.wolframalpha.com/input/?i=solve+x%5E2%2By%5E2%2B6y%2B5%3D0,+x%5E2%2By%...

*November 17, 2016*

**math**

a = bh/2 so, 5b/2 = 15

*November 17, 2016*

**Linear Programming - The Graphical Method**

This web site is very useful: http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html

*November 17, 2016*

**Math (equation of tangent line)**

2xy-1=(x+y+1)^2 2y + 2xy' = 2(x+y+1)(1+y') 2y + 2xy' = 2(x+y+1) + 2(x+y+1)y' y' (2x - 2(x+y+1)) = 2x+2 y' = -(x+1)/(y+1) So, your derivative is ok. when y = -1, x = -1, so y' = 0/0 so, what happens near (-1,-1)? If y = -1+h, x = -1+h+?(2h) so, y'...

*November 17, 2016*

**Pre-Calc**

sin(kx) has period 2?/k tan(kx) has period ?/k so, crank it out.

*November 17, 2016*

**ELITRICAL MATH! (LAST ONE FOR TODAY, HOPEFULLY!)**

divide cost/quantity $1.49/3ft = $0.4967/ft and similarly for the other one. Then compare

*November 17, 2016*

**Math**

8^-2 = 1/8^2 = 1/64 4^-2 * 2^0 = 1/16 * 1 = 1/16 5^(2-1+3) = 5^4 Your typos make things hard to read

*November 17, 2016*

**Math**

yes.

*November 17, 2016*

**Math**

just substitute: y = x-2, so x^2 - x(x-2) + 3(x-2)^2 = 15 3x^2 - 10x - 3 = 0 solve for x, than y=x-2.

*November 17, 2016*

**Math**

6 * 1/3 = 2

*November 17, 2016*

**Algebra**

You have two circles: x^2 + (y+3)^2 = 6 (x - 9/2)^2 + y^2 = 105/4 Naturally, they intersect where x^2+y^2+6y+3 = x^2+y^2-9x-6 6y = -9x-9 y = -(3x+3)/2 Subbing that into one of the equations, x^2+(3x+3)^2/4-9x-6=0 13x^2 - 18x - 15 = 0 x = 1/13 (9±2?69) y = -3/13 (11&...

*November 17, 2016*

**Math**

well, g = f-7 so what do you think?

*November 17, 2016*

**Math**

The only reason I can think of is that a measurement is subject to error (and is really only a decimal approximation), whereas the PT results is exact.

*November 17, 2016*

**Differential Calculus**

I do not know what cos^y means. I'll just use cosy and you can fix it as needed. x^2 cosy - siny = 0 2x cosy - x^2 siny y' - cosy y' = 0 y' = (2x cosy)/(x^2 siny + cosy) so, at (0,?), y' = 0 Since the tangent is horontal, the normal is vertical, and the ...

*November 17, 2016*

**maths**

40 = 360/9 so, 1/9 of the whole area.

*November 17, 2016*

**maths**

35 min = 7/12 of an hour. That is, 7/12 of the circumference of a circle with radius 6 cm. so, ...

*November 17, 2016*

**Algebra**

correct

*November 17, 2016*

**Math**

add up the total points so far. He needs 4*59 so, how many points short is he?

*November 17, 2016*

**Maths**

Check with "Ed" below ...

*November 17, 2016*

**Maths**

h = 1 + 3t - 4.9t^2 You forgot about gravity

*November 17, 2016*

**Maths**

h - 4.9 * 1.5^2 = 0 v = -9.8t

*November 17, 2016*

**Math**

try here: http://davidmlane.com/hyperstat/z_table.html

*November 17, 2016*

**Geometry**

also, 19x-11 = 10x+7

*November 17, 2016*

**maths**

ok, now what?

*November 17, 2016*

**math**

by, not bye 29+16/9 = 30 7/9 I assume you meant (28+16)/9 = 45/9 = 5 Online, parentheses make a big difference!

*November 17, 2016*

**math**

Looks like a good unit to study, all right. Do you have any specific questions that are causing you difficulties? Do not expect someone here to provide you with all the answers...

*November 17, 2016*

**Scale Math HELP!!!!!!!!!!**

1.29 * 6.5 * (how many sides?)

*November 17, 2016*

**Fizik**

All your numbers are missing, but just find the net force and then use F = ma v = at s = 1/2 at^2

*November 17, 2016*