Monday

October 24, 2016
Total # Posts: 45,210

**Maths**

the line intersects where -x^2-x-8 = ax+1 x^2 + (a+1)x + 9 = 0 In order for there to be a single intersection, the discriminant must be zero. That is, (a+1)^2 - 36 = 0 See what you can do with that. http://www.wolframalpha.com/input/?i=plot+-x%5E2-x-8,+y%3D5x%2B1,+y%3D-7x%2B1...

*October 24, 2016*

**Maths**

the differences are 13,15,17, ...

*October 24, 2016*

**Math**

d^2 = 2s^2

*October 24, 2016*

**algebra**

a+4d = 2(a+d)+1 a+9d = 2(a+3d)+3 Now crank it out.

*October 24, 2016*

**Algebra**

These do not factor over the rationals. You need to complete the square of use the quadratic formula.

*October 23, 2016*

**Geometry**

to get the vertex angle θ, sin(θ/2) = 7/24 Once you have θ, the other two angles are equal, and they all three add up to 180.

*October 23, 2016*

**maths**

Multiples of 11 which end in 7 are 11*17 = 187 11*27 = 297 ... 11*87 = 957 So, how many are there?

*October 23, 2016*

**Math**

more frequent compounding, more money.

*October 23, 2016*

**Math**

this is not hard. Just start listing the sums: ABDM 1983: 918+318+813=2049 ... There are only 24 ways to arrange the numbers. Crank it out. I think you can eliminate all the ones where A is not 1. That makes one of the other leading letters be 1; not a likely choice.

*October 23, 2016*

**Math**

start listing the powers. You will see a pattern which makes it easy to solve this problem.

*October 23, 2016*

**math**

If he has 93 fruits, how do you come up with 6 bags of 8 fruits?

*October 23, 2016*

**Maths**

If she shoots x baskets, she scores 2x points, so she needs 94 + 2x = 16*12 and that's "in all" not "at all"

*October 23, 2016*

**Math**

review Euler's Formula for polyhedra.

*October 23, 2016*

**math**

?? The sides appear not to be integers. I guess there must be a border included in the length. √800 = 20√2 So, I guess there are 10√2 small squares across and down.

*October 23, 2016*

**Math**

Since it's going down, subtract another 40 feet: -28-40

*October 23, 2016*

**Math limits**

#1 is correct, but could be done directly. 3/x^2 -> 0 so, the limit is just 4x, which -> ∞ For #2, no tricks are involved. x^2 -> 0, so -(x^2-4)/(x^2-1) -> -(0-4)/(0-1) = -4

*October 23, 2016*

**Algebra**

(11+2w)(8+2w) = 154 You add 2w because both sides have a border. Note that 154 = 14*11

*October 23, 2016*

**math**

"increased 5 times" could mean x(+x) 5 times = 6x or x*5 = 5x I'll assume the latter, but you can fix it if you need to (5x+3)/2 = x - 0.3

*October 23, 2016*

**Math**

df/dx = 3, so df = 3 dx dx = -0.1, so ...

*October 23, 2016*

**Math**

just write what they gave you 99 ∑ 1/(k(k+1)) k=1

*October 23, 2016*

**phy101**

geez - same problem, no fixes made.

*October 23, 2016*

**N.E.U**

You want to specify all the data and try again? and that's m/s^2, not some bogus m.s.s which is meaningless.

*October 23, 2016*

**value**

why all those tedious words? It appears that you mean x+9 = 2 1/4 x On the other hand, you opaque language makes it unclear.

*October 23, 2016*

**math**

Sue is 2 mi/hr faster. So, how long to make up the 1/2 mile?

*October 23, 2016*

**Physics**

momentum (mv) is conserved. So, if v is the same, m is the same.

*October 23, 2016*

**math calculus**

If the height is y and the width is x, then a = (x+10)(300/x + 20) now find da/dx = 0 for minimum area.

*October 23, 2016*

**maths**

a common ratio indicates a g.p. (or, as nasra calls it, a go) S10 = a(r^10-1)/(r-1) a(2^10-1) = 93 a = 93/1023 and that's "the sum ... is 93"

*October 23, 2016*

**mathematics**

(2/3)x = (5/8)(31-x)

*October 23, 2016*

**Math Homework**

I assume you have some formula for seeding the teams?

*October 23, 2016*

**math**

what's the trouble? Just write down what they tell you: p = x + 4x+10 + x+3

*October 23, 2016*

**math**

∫ sin2x/√(1+cos^2x) dx u = 1+cos^2x du = -2cosx sinx ... ∫ x/[(x^2-1) ln(x^2-1)] dx u = ln(x^2-1) du = 1/(x^2-1) * 2x dx ...

*October 23, 2016*

**Algebra**

40 days and 40 nights. Now, to find Ali's number, solve 6x-30 = 78

*October 23, 2016*

**Math**

LCM(12,18) = ?

*October 23, 2016*

**Mathematics**

g^-1(x) = log3x

*October 23, 2016*

**Mathematics**

or, you know that one root is at (0,0) and since the vertex is at x=2, the other root must be at (4,0). So, y = ax(x-4) y(2) = -8, so -8 = a*2(-2) a = 2 y = 2x(x-4) This agrees with Reiny's solution above.

*October 23, 2016*

**science**

take a look here: http://physics.stackexchange.com/questions/99117/why-gravity-decreases-as-we-go-down-into-the-earth

*October 23, 2016*

**Maths**

In a square (or rhombus), the diagonals are perpendicular. Since your diagonals have a 45° angle between them, the two semi-diagonals form an isosceles triangle with vertex angle 45° and equal sides of length 3. I expect you can draw that, eh? The length is 5.544 and ...

*October 23, 2016*

**math**

what - you can't count from 20 to 30?

*October 23, 2016*

**Physics**

it will be 10/3^2 as much try proofreading what you type before finally posting, ok?

*October 23, 2016*

**math (horizontal tangent line)**

You are correct. The slope is always positive. see the graph at http://www.wolframalpha.com/input/?i=x%5E3%2Bx

*October 22, 2016*

**Present Value Math**

just plug your numbers into your PV formula. You do have the formula, right? If not look it up in your text or online.

*October 22, 2016*

**Math (Calculus)**

If you truly have no idea, you clearly have not studied your text. In this case, google is your friend. It will provide many discussions (wikipedia is a good one), as well as youtube videos. When you are really lost, and need general instruction, start with google. This site ...

*October 22, 2016*

**Math**

OR, P - 2 1/3 = -8/12 = -2/3 ...

*October 22, 2016*

**Math**

12(p) - 12(2 1/3) = -8 ...

*October 22, 2016*

**Calculus**

a = πr^2 da = 2πr dr The error is ∆a which for small errors is approximately da. So plug and chug. Now, what does it all mean?

*October 22, 2016*

**Physic**

If we let A=(0,0) then the rider ends up at C=(2.6,1.5) Now just use the law of cosines to get the distance, and note that the angle from B to C is tanθ = 1.5/2.6 But that is the bearing of C from B. You want the opposite direction to get from C to B.

*October 22, 2016*

**integrals**

you can't use the power rule because that says ∫ u^n du = 1/(n+1) u^(n+1) But if you let u = x^2+4 du = 2x dx So, you do not have ∫ u^-2 du because you would need a 2x on top. Instead you need to use a trig substitution. (Well, I guess you don't need to, ...

*October 22, 2016*

**Math**

What's the trouble? Just write down what they told you: b = 3.40*19 + (35.00+14.95)d

*October 22, 2016*

**Math**

A car rental agency charges $35 per day to rent a car and $14.95 per day for a global positioning system (GPS). Customers are charged for their full tank of gas at $3.40 per gallon. A car has a 19 gallon tank and a GPS. a) Write a function rule for ...

*October 22, 2016*

**math**

you just need to remember your point-slope form of a line, and you get y-5 = -6(x+12) Then just rearrange as needed.

*October 22, 2016*

**Math**

Note that the maximum area is achieved when the fencing is divided equally among the lengths and widths: 1200 each.

*October 22, 2016*

**Science**

... emotions: Exhilaration!!!

*October 22, 2016*

**physics numerical**

since mv is the same for both bodies, m1/m2 = v2/v1 15/2000 = v2/v1 Now if you can see your way to specifying v1, you can find v2.

*October 22, 2016*

**Math**

A car rental agency charges $35 per day to rent a car and $14.95 per day for a global positioning system (GPS). Customers are charged for their full tank of gas at $3.40 per gallon. A car has a 19 gallon tank and a GPS. a) Write a function rule for ...

*October 22, 2016*

**math**

http://www.jiskha.com/display.cgi?id=1477157306

*October 22, 2016*

**math**

this is just like the other one. The car dropped in value by $7500 in 5 years. That is $1500/year, so the slope of the line y = mx+b is -1500 That means y = -1500x + b Now you just have to find b so it fits the data.

*October 22, 2016*

**Math**

3700(1 + .07/2)^(2*12.5) = ?

*October 22, 2016*

**Computer**

good grammar and spelling!

*October 22, 2016*

**Repost(Physics)**

well, it clearly grows by 2 km/hr every hour. So, that means it grows by 1/1800 km/hr every second.

*October 22, 2016*

**bctc**

Think of the lines y=3x, y=5x See where that takes you.

*October 22, 2016*

**calculus**

There are lots of similar questions answered below in the related questions section. And unless it's a rain tank, you probably mean "radius."

*October 22, 2016*

**Calculus**

surely you can find the y-intercept!! Just set x=0 As for x- intercepts, note that y = x^2 √(3-x) √(3+x) now where does x^2 √(3-x) √(3+x) = 0 ??

*October 22, 2016*

**Math, Functionsons**

as I mentioned in your previous post, The domain of all polynomials is (-∞,∞) Now, note that x^2 >= 0 so, x^2-2 >= -2 The range is thus [-2,∞) Think of the graph. Its vertex is at (0,-2).

*October 22, 2016*

**Describing Data**

well, the average frequency for those years is (6605+712+88011+1790)/4 = 24,280 But, as you can see, any linear model will be a pretty poor predictor, since the values are so widely scattered. But, if you broke the data into groups of 5-10 years, things might even out some.

*October 22, 2016*

**Math**

|-4| = 4 |+4| = 4 ... and so on

*October 22, 2016*

**algebra 1**

y = 2 + (20-2)/6 x = 2+3x This comes about because in 6 lessons you have learned 18 words. That's 3 words/lesson, starting with 2.

*October 22, 2016*

**math**

get what? They told you that the value dropped from 20K to 14K in two years. If you can't see how that relates to the slope of the graph, then you seriously need to review your text or look at examples online. Since it dropped 3K in one year, and a year after it was bought...

*October 22, 2016*

**math**

it dropped 6K in 2 years. That's 3K per year. So, it started at 3K more than 20K. y = 23000 - 3000x

*October 22, 2016*

**Algebra**

5646000 * 1.047^n = 13000000000

*October 22, 2016*

**Algebra**

$15/hr

*October 22, 2016*

**Algebra**

do you not see the relation between hours and money?

*October 22, 2016*

**Math, Functions**

the domain of all polynomials is (-∞,∞) There is no value of x which is not allowed. Since the graph is a sloping straight line, it extends forever in both directions, so the range is also (-∞,∞)

*October 22, 2016*

**Math - correction**

nope. only 13 are boys. 22:13

*October 22, 2016*

**Math**

counting boxes, with x sold on Monday, x + x-3 = 15 12x is the number of pencils.

*October 22, 2016*

**math**

the lot will be 37.5 by 25 where the extra piece is parallel to the short sides.

*October 22, 2016*

**math**

the monthly charge for A is clearly 14.45 (0 minutes) So, for B, $(22.10-14.45)/45min = $0.17/min

*October 21, 2016*

**Math**

just multiply by 45 512.

*October 21, 2016*

**Math**

56000+9x = 16x

*October 21, 2016*

**calculus**

M'(x) = .0009x^2 - .132x + 4.64 Now just evaluate M' for your years.

*October 21, 2016*

**Algebra**

A is correct B is correct if the line goes through (-4,0)

*October 21, 2016*

**Math**

fix typo revenue = p*demand then take derivative.

*October 21, 2016*

**Calculus**

for f"=0 you need sin2x - cos4x = 0 sin2x - (1 - 2sin^2(2x)) = 0 2sin^2(2x) - sin(2x) + 1 = 9 (2sin2x+1)(sin2x-1) = 0 sin2x = -1/2 sin2x = 1 Count the solutions in the interval. Looks like ten to me.

*October 21, 2016*

**physics**

use the Pythagorean Theorem, since the directions are perpendicular.

*October 21, 2016*

**Maths**

45-(30+20-8) = 3

*October 21, 2016*

**math**

well, a*10^5 = 2000

*October 21, 2016*

**math**

(-28.9-(-79.9))/(19.125-12.75-(79.9/18.8)) = 24.0 ft/min

*October 21, 2016*

**Calvary School**

9/4 yards, 3 inches

*October 20, 2016*

**Physics**

8*10 + 2(-5) = (8+2)v

*October 20, 2016*

**algebra/AP physcis**

Can't be done. If you move the 1.2v^2/.6 to the left, you wind up with -.2v^2/.6 = 9.8 The left side is negative and the right side is positive. I suspect a typo somewhere, or an error in devising the equation.

*October 20, 2016*

**Calculus**

y = (x^2 +2x)^3(x+2) = x^3(x+2)^4 y' = 3x^2 (x+2)^4 + x^3 * 4(x+2)^3 * 1 = x^2(x+2)^3 (3(x+2) + 4x) = x^2(x+2)^3(7x+6)

*October 20, 2016*

**Math**

if p>0, then q<0 and -3p+4q is negative. So, p<0 and q>0 -3p > 0 4q > 0 so -3p+4q > 0

*October 20, 2016*

**Math**

huh?

*October 20, 2016*

**GCF**

940 = 20*47 420 = 20*21 940-420 = 20(47-21) = 20*26 = 520

*October 20, 2016*

**math**

f(g) = 4g-5 = 4(3x)-5 = 12x-5

*October 20, 2016*

**Math**

sides have ratio 36/22 areas have ratio (36/22)^2

*October 20, 2016*

**MATH**

x(t) = -t + t^3/6 v(t) = dx/dt = -1 + t^2/2 I think you can now answer the questions if you think a bit.

*October 20, 2016*

**Math**

well, the triangle's 3 sides can each intersect with two sides of the rectangle, making six intersections. Now see what you can do with the circle.

*October 20, 2016*

**Algebra**

3.29, naturally. cost = 3.29 * gals

*October 20, 2016*

**pre-calc**

Do you mean e^-t cost + e^-t sint = 0? If so, factor out the e^-t and you have e^-t (cost - sint) = 0 e^-t is never 0, so that leaves sint = cost or tant = 1 I think you can work with that, eh? Remember all four quadrants.

*October 20, 2016*