Monday
January 23, 2017

Posts by steve

Total # Posts: 47,961

Math
a+c = 163 11a+6c = 1578
December 15, 2016

ST KYLINS
My digits in the ones period are zeros. xxx,xxx,000 now what else do you know?
December 15, 2016

calculus
this should help http://www.jiskha.com/display.cgi?id=1481848543
December 15, 2016

Maths
I agree. Since the distance between the foci is only 2, there is no way that the condition can be met.
December 15, 2016

Maths
google is your friend. Try this to get going: https://people.richland.edu/james/lecture/m116/conics/hypdef.html
December 15, 2016

Algebra II
V = k/P, so VP = k, a constant so, you want V so that 2.2V = 20*16 By the way, L/cm^2 is not pressure. 1L = 1000cm^3, so L/cm^2 = cm Pressure is force/area, as in N/m^2 I've never heard of this L/cm^2 unit. But then, I'm not a physicist...
December 15, 2016

Algebra
h^2+27^2 = 38^2
December 15, 2016

algebra
9.6/3.2 * 10^(2-5) = 3.0 * 10^-3
December 15, 2016

algebra
2.5^4 * (10^-2)^4 = 39.0625 * 10^-8 = 3.90625 * 10^-7
December 15, 2016

Math
so the square must be 4x4 what do you mean when you say "all sides"? Only the sides, not the rows or columns, or diagonals? For 4 numbers to add to 25, either one or three of them must be odd. See what you can do with that.
December 15, 2016

calc
e^(x^2-x+a) if x < 1 as x->1-, f(x) -> e^a (4^x-x^2)) if 1<x<2 as x->1+, f(x) -> 4^1-1 = 3 as x->2-, f(x) -> 4^2-2^2 = 12 6In(x-b) if x>2 as x->2-, f(x) -> 6ln(2-b) so, we need e^a = 3 a = ln3 6ln(2-b) = 12 ln(2-b)=2 2-b = e^2 b = 2-e^2 But ...
December 15, 2016

Calc
?(5-x) is defined for x<5 so, using x<1 works there lnx is defined for x>0 so, x>1 works there except where x=25 So, f(x) is defined and continuous on (-?,1)U(0)U(1,25)U(25,?)
December 15, 2016

science
none, if it's limestone
December 15, 2016

algebra
just move the decimal point. to the left for negative powers to the right for positive powers
December 15, 2016

precalculus
Nope. B First, show that P(1) is true. Then you assume C so you can prove D.
December 15, 2016

precalculus
Nope. A.
December 15, 2016

precalculus
yep
December 15, 2016

Calc
consider the case f'(x) = x
December 15, 2016

precalculus
since we're dealing with powers of 2, I'd pick B Besides, if k>1, (k+1) ? (k+k)
December 15, 2016

precalculus
correct, if you use a few parentheses: 3^(k+1) > (k+1)*2^(k+1)
December 15, 2016

Maths
Find the roots of the polynomial. Then find the slope at those points. y'=2-2x Then use the point-slope form to get the line equations. Do the same for the normals, with slope -1/y' Find the intersections, and then you can measure the triangle. Here's a start, ...
December 15, 2016

Geometry
So, how's that copy/paste working out?
December 15, 2016

math
so what? It was blazing hot at noon.
December 15, 2016

Math
If the dimensions are x,y,z, you need to find the minimum of 2xy+2xz+2yz using xyz=729 I think you will find that a cube does the job, just as a square minimizes the perimeter for a given area.
December 15, 2016

Math
b = 2c s = b-10 b+c+s = 100 Now just crank it out.
December 15, 2016

Algebra
Oh, right. C is indeed correct.
December 15, 2016

Algebra
if y varies directly with x, y=kx. So, y/x is constant. It is clear that this is not the case. Especially not y=10x. That would give the table 8|80 16|160 24|240 How ever did you arrive at that answer?
December 15, 2016

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

math
42
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

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