Monday

February 27, 2017
Total # Posts: 48,834

**precalculus**

I pick D. Then you have to add a term to both sides: 1+4+7+10 + + (3k-2)+(3(k+1)-2) = k/2 (3k-1) + (3(k+1)-2) and then show that k/2 (3k-1) + (3(k+1)-2) = (k+1)/2 (3(k+1)-1) watch the parentheses when working online. Things can be misread due to the lack of text formatting.

*December 15, 2016*

**Math**

32 days is 4 half-lives, so divide by 2^4 = 16

*December 15, 2016*

**Math**

seems legit to me. Though if they are in slope-intercept form, y is isolated, so substitution would work equally well.

*December 15, 2016*

**math**

reflect through x=3: (x,y)->(3-(x-3),y) = (6-x,y) reflect through y=x: (x,y)->(y,x) so, now just combine those two transformations: (x,y)->(6-x,y)->(y,6-x)

*December 15, 2016*

**Maths**

each gardener takes 3*90 = 270 minutes to do the job alone. So, since 15 = 270/18 It will take a total of 18 gardeners.

*December 15, 2016*

**Maths**

(a+b+c)/3 = 2d (a+b+c+d)/4 = 28 so, 6d + d = 4*28 ...

*December 15, 2016*

**Math**

No way to tell, since you give no information about e and F.

*December 15, 2016*

**Calculus**

f' = 3x^2+2ax+b Now just find a and b so that f' has factors (x-1)(x-5) Then you can determine the rest using f".

*December 15, 2016*

**Maths science his french**

use Snell's Law

*December 15, 2016*

**Math**

6(43-35) ...

*December 15, 2016*

**Math**

11x + 55 = 11(x+5)

*December 15, 2016*

**Math**

4*5 + 4*1/8 = 20 1/2

*December 15, 2016*

**Maths**

The diagonals are perpendicular, and bisect each other. Draw the diagram. Each triangle formed is a 3:4:5 right triangle.

*December 15, 2016*

**Math**

60 hot dogs per year? per month? per week?

*December 15, 2016*

**physics**

200/30 * 2pi rad/s

*December 15, 2016*

**Algebra**

x^2 + y^2 + 10x + 8y = 40 x^2+10x + y^2+8y = 40 x^2+10x+25 + y^2+8y+16 = 40+25+16 (x+5)^2 + (y+4)^2 = 81 That help?

*December 15, 2016*

**Math algebra**

well, you have the equation. Just plug in Ao = 1000 t = 50

*December 15, 2016*

**Math**

no idea. what fraction is paid?

*December 15, 2016*

**physics**

Consider that A+B and A-B are the diagonals of a parallelogram. When are the diagonals equal?

*December 15, 2016*

**physics**

4.9t^2 = 75 the 2nd part depends on the horizontal speed, which is constant.

*December 15, 2016*

**algebra 1**

bh/2 = 27 (h+3)h/2 = 27 ...

*December 15, 2016*

**Math**

3/4 (8u-12)

*December 14, 2016*

**math**

I predict it will be y = a cos(bx)

*December 14, 2016*

**Pre-calculus**

However, r = -5/(2cos? + sin?) is a line. r(2cos?+sin?) = -5 2x+y = -5 Now the intercept isn't so hard to find, eh?

*December 14, 2016*

**Math**

no way to tell. depends on the "steady rate"

*December 14, 2016*

**Algebra**

(a) after x pumps, we have sit(x) = 3 + 2x stand(x) = 3 * 1.2^x Now just use those functions to solve for the needed values.

*December 14, 2016*

**Science**

recall that F = ma

*December 14, 2016*

**math**

what's to justify? It has a steepness...

*December 14, 2016*

**Algebra**

clearly, at x = -2 and 1.

*December 14, 2016*

**Math**

11th term is a+10d that will make a difference.

*December 14, 2016*

**Math**

try putting things into standard form: (2x+6)(3x-1)=2 6x^2 + 16x - 6 = 2 6x^2 + 16x - 8 = 0 or 3x^2 + 8x - 4 = 0 Now just use the quadratic formula.

*December 14, 2016*

**algebra**

it already is. Just add the power of 10 3.000052 * 10^0 Now, if you mean that problem #3 was .000052, that is 5.2 * 10^-5

*December 14, 2016*

**Math**

why use 50 for the common denominator, when 10 works just as well? 13/5 + 29/10 = 26/10 + 29/10 = 55/10 Now subtract that total from the 11 hours (110/10) needed, and you still need 55/10 = 5 1/2 275/50 is 5 1/2, not 5/2.

*December 14, 2016*

**algebra**

moving the decimal point 6 places to the right, we get 6.98 * 10^-6

*December 14, 2016*

**Math**

(1+r)^4 = 1.75

*December 14, 2016*

**Math**

How about some parentheses? Just guessing here, I read e^(4x-3) = 2e^(2x) No idea what the final 1 is. Anyway, I'll work this, and then you can fix it if necessary. Taking logs of both sides, we get 4x-3 = ln2 + 2x 2x = 3+ln2 x = (3+ln2)/2 ln(2x+6) - ln(3x-1) = ln(2) (2x+6...

*December 14, 2016*

**Math**

when 1.026^x = 3

*December 14, 2016*

**pre calc**

so, list the values for x calculate and list the values of y. Something hard about that?

*December 14, 2016*

**Math**

A is decreasing when A' < 0 The growth rate G' is maximal when its derivative (G") is zero. Just as G has a max when G' = 0.

*December 14, 2016*

**math**

depends on how many grades you already have. The more low grades you have for the 76% average, the higher grade you will need to raise it to 81%.

*December 14, 2016*

**Business Math**

revenue = price * demand Assuming the usual carelessness with parentheses, r(x) = x*p(x) = x(50/(0.01x^2 + 1)) The maximum revenue is found at x=10. See the graph and other info at http://www.wolframalpha.com/input/?i=x(50%2F(0.01x%5E2+%2B+1))

*December 14, 2016*

**precalculus**

The 2nd difference is not 1 (7-6). The 2nd difference is the sequence of differences of the 1st differences. You have sequence: 7, 6, 7, 10, 15, 22,... 1st diff: -1,1,3,5,7,... 2nd diff: 2,2,2,2,... 2nd ok 3rd. Did you actually try your formula? (Assuming you meant 21.5x) y(1...

*December 14, 2016*

**precalculus**

#1 If you meant Pk=2^(k-1)/k! then Pk+1 = 2^k/(k+1)! #2 If Pk = 7 + 13 + 19 + ...+[6(k - 1)+1] + (6k + 1) Pk+1 = 7+13+...+(6k+1)+(6(k+1)+1) = 7+13+...+(6k+1)+(6k+7) #3 The first step is to show that P(1) is true #4 You assume that 3 + 11 + 19 + 27 + … + (8n - 5) = n(4n - ...

*December 14, 2016*

**MATH FOR LIBERAL ARTS**

well, 1 in = 2.54 cm so just multiply the height (in inches) by 2.54

*December 14, 2016*

**precalculus**

come on -- just plug in k+1 for k: Pk+1 = (2(k+1)-1)/(k+1)! = (2k+1)/(k+1)!

*December 14, 2016*

**precalculus**

the differences are 0,2,4,6,8,... Tn+1 = Tn + 2(n-1) so, Tn = n^2-3n+5

*December 14, 2016*

**precalculus**

I assume you mean n! > 2^n 4! > 2^4 for n>4, n! = 4!*5*6*...*n > 2^4*2*2*2...*2

*December 14, 2016*

**Maths**

The set 1 2 5 7 10 has mean=5 median=5 Now, if you don't want integers, then fudge the values a bit. 1.1 2.1 5 6.9 9.9 The mean is still 5. Since there are an odd number of values, the median must be the center number. If it is 5, then the median is an integer. I see no ...

*December 14, 2016*

**Calc 2 Urgent Surface Area of Revolution Question**

You can do that too.

*December 14, 2016*

**Calc 2 Urgent Surface Area**

Oh yeah. Sorry I did the volume instead. Consider the surface as a pile of circular rings, each with circumference 2?r. So, the surface area is S = ?[0,1] 2?x ds but ds is a small piece of the line, of length ds^2 = dx^2+dy^2 = dx^2 + (4dx)^2 = 5dx^2 S = ?[0,1] 2?x?5 dx = ?5...

*December 14, 2016*

**math**

a fraction of what? a kg? a ton? an ounce?

*December 14, 2016*

**Math**

Is this some kind of truncated triangular pyramid? Your description is a bit vague.

*December 14, 2016*

**precalculus**

same as the others. pick values for ?, figure x and y, then just plot the points! Note that since cos^2?+sin^2?=1, ((x-2)/3)^2 + (y/2)^2 = 1 Looks like an ellipse to me.

*December 14, 2016*

**precalculus**

you can either (a) find and fix my typo (b) read bobpursley's solution, which is correct.

*December 14, 2016*

**precalculus**

just like the other one! pick some values for t, calculate x and y, and plot the points. First, decide whether you meant x=?(t^2+2) or x=?t^2 + 2) I suspect the former, since ?t^2 = |t| So, x is basically just t y is basically just t. The graph will be almost a straight line ...

*December 14, 2016*

**precalculus**

No. x = 2 + 3cos? NOT x = (2+3)cos?

*December 14, 2016*

**intermediate algebra**

you have the equations. Now just solve them.

*December 14, 2016*

**Calc 2**

No calculus need for this one. It's just a cylinder with a cone cut out. r=1 h=4 v = ?r^2h - ?/3 r^2h = 2?/3 r^2h = 8?/3 Ok ok. If you want to use calculus, then with shells, v = ?[0,1] 2?rh dx where r=x and h=y=4x v = ?[0,1] 2?x*4x dx = 8?/3 using discs (washers) you get ...

*December 14, 2016*

**precalculus**

no idea. It's a set of parametric equations. You can use pi as a value if you wish.

*December 14, 2016*

**precalculus**

no idea. What does pi have to do with it?

*December 14, 2016*

**precalculus**

pick some values for t, calculate x and y, and plot the points. Nothing hard about that. You can tell it will be a parabola, since you already figured out that x = (2y+2)^2 - 6

*December 14, 2016*

**Algebraic equations real life problems**

You have your two equations. 3b = 2+a 3a-b = 2+a+2b rearrange things a bit and you have a - 3b = -2 2a - 3b = 2 subtract and you have a=4 so, b=2

*December 14, 2016*

**Algebraic equations real life problems**

as you know, perimeter is 2(length+width) With no actual numbers provided, it is impossible to assign values to a and b.

*December 14, 2016*

**Math**

9/12 - 8/12 = ?

*December 14, 2016*

**Calculus**

v = x^2y 4x+y <= 6 see where that takes you.

*December 14, 2016*

**maths**

given the murky question, 36 seems as good an answer as any...

*December 14, 2016*

**physics**

face north turn eastward (clockwise) 28 degrees. Now you are facing N28°E

*December 14, 2016*

**Math help please I do not understand it**

7 3/5 what? feet? meters? inches?

*December 14, 2016*

**OBJECT ORIENTED PROGRAMMING**

you expect someone here to undertake such a project and do it all for you? Don't ask much, do you?

*December 14, 2016*

**Math**

can't spell, either, eh?

*December 14, 2016*

**math**

x + x+1 + x+2 = 126 ...

*December 14, 2016*

**math**

yes. send your check to me and I'll email them to you.

*December 13, 2016*

**math**

I predict that it was a bottle of nail polish.

*December 13, 2016*

**gms**

post the file online, rather than expecting us to access it on your computer...

*December 13, 2016*

**Algebra**

x^2/25 + y^2/100 = 1 the major axis is vertical. a = 10 b = 5 c^2 = a^2-b^2 = 75 The foci are at (0,±c)

*December 13, 2016*

**Math**

I'll do the x's. You can then use the steps for the t's: 4(3x - 1)= 3 + 8x - 11 12x-4 = 8x-8 4x = -4 x = -1

*December 13, 2016*

**Math**

3C2 = 3

*December 13, 2016*

**math**

12/3 = 4 lockers So, 4/3 cans for 4 lockers ... -(-0.45) ...

*December 13, 2016*

**Math**

remember these? http://www.sosmath.com/trig/prodform/prodform.html

*December 13, 2016*

**maths**

If you meant (11-w)/4 = 1-w 11-w = 4-4w 3w = -7 w = -7/3 If you meant 11 - w/4 = 1-w 3w/4 = -10 w = -40/3

*December 13, 2016*

**Math Percents: Please help!!**

nope. 240 * 1.15 = 276 264 is a 10% increase: 240+24

*December 13, 2016*

**Algebra**

well, the elements must match, so -3x = 12 7 = 7 2y = x+y I think that you can take it from there, yes?

*December 13, 2016*

**Math Help**

(g?f) = g(f) = 9f+3 = 9((x-3)/(x9))+3 And you can massage that as you like (whatever x9 means...)

*December 13, 2016*

**Trig Question**

If you meant 6cos(3?)/2+3=0 that is just 3cos3? + 3 = 0 cos3? = -1 3? = ? ? = ?/3 The period is 2?/3, so ? = ?/3 + k(2?/3) = ?/3, ?, 5?/3 see the graph at http://www.wolframalpha.com/input/?i=plot+6cos(3%CE%B8)%2F2%2B3%3D0,+0+%3C%3D+%CE%B8+%3C+2pi Now, if you meant 6cos(3?/2)+...

*December 13, 2016*

**precalculus**

Huh? Use your numbers: cot2? = (1-1)/6 = 0 2? = 90° ? = 45° http://www.wolframalpha.com/input/?i=x%5E2%2B6xy%2By%5E2-6%3D0

*December 13, 2016*

**precalculus**

tan2? = B/(A-C)

*December 13, 2016*

**precalculus**

come on. just substitute it into the other equation. t = 2y+2 x = t^2-6 = (2y+2)^2-6 = ... It is clearly a horizontal parabola

*December 13, 2016*

**precalculus**

well, t = 2y+2, so use that

*December 13, 2016*

**precalculus**

well, |cos3?| <= 1 cos3?=0 when 3? is an odd multiple of ?/2

*December 13, 2016*

**precalculus**

the ellipse looks good, but y=-t^2 x=-t^2+4 becomes x-y=4 not x-y^2 = 4 same for t^3

*December 13, 2016*

**Pre-algebra PLease help**

I get: 1C 2B 3C (2/3 is just 2 * 1/3) 4A 5A 12 is 50% of 24 That is a good first estimate. However, you are correct that 11 is closer (.48*23.95 = 11.49). I would have guessed 12, but 48% is a bit less than 50%, and 23.95 is a bit less than 24, so my estimate was a bit high. ...

*December 13, 2016*

**chemistry**

how many moles of SiO2? Each mole needs 3 moles of C. similarly for the other parts. work with moles, then back to grams.

*December 13, 2016*

**ALGEBRA 2**

g(x) = f(x-8)-7

*December 13, 2016*

**algebra**

ummm ... h?

*December 13, 2016*

**math**

cosx/(secx-tanx) = cosx / (1/cosx - sinx/cosx) = cosx / (1-sinx)/cosx = cos^2x / (1-sinx) = (1-sin^2x)/(1-sinx) = (1+sinx)(1-sinx)/(1-sinx) = 1+sinx why the word "plus"? You have a missing + key?

*December 13, 2016*

**precalculus**

Hmmm. The standard form for the polar conics is r = ep/(1 + e sin?) While your equation looks correct, I'd have written it as r = (5/2) / (1 + (5/4) sin?) to make it clear what the parameters are. Or, if you dislike fractions, r = 10/(4+5sin?)

*December 13, 2016*

**Alegrebra 2**

horizontal axis or vertical? Where is the vertex or directrix? You need to give more information. Depending on the vertex, many parabolas have that focus.

*December 13, 2016*

**Math**

construct AB with length 4.8 find the midpoint M of AB with M as center, draw a circle P with radius 3.6 with B as center, draw a circle Q with radius 5.2 Where P intersects Q is C.

*December 13, 2016*

**precalculus**

the rotation angle ? is such that tan2? = B/(A-C)

*December 13, 2016*