# Posts by STEVE

Total # Posts: 49,597

**Geometry**

Hmmm. I can't seem to make them out ...

*February 28, 2017*

**Math**

well, he used the distributive property of multiplication...

*February 28, 2017*

**cal**

Nope. Show your work, and we can see what went wrong. Don't forget your Algebra I now that you're taking calculus...

*February 28, 2017*

**cal**

recall that the average rate of change on [a,b] is (f(b)-f(a))/(b-a) now just plug and chug.

*February 28, 2017*

**Math - implicit differentiation**

5x^2 + 2x + xy = 2 10x + 2 + y + xy' = 0 Now just plug in your numbers and solve for y'.

*February 28, 2017*

**Math**

24 kids get evenly bitten by 1152 ants. How many bites did each one get?

*February 28, 2017*

**math 1**

so, y = -1 now you can find x.

*February 28, 2017*

**math**

1 wafer = 64/4 = 16 grams 3200/16 = ? wafers/box

*February 28, 2017*

**math 1**

so, you got x=1 Use that in the other equations and see whether you get the same value of y for each. If so, then that x and y are the solution.

*February 28, 2017*

**Math grade 6**

so, what's the volume of one block? ya gotta start somewhere, eh?

*February 28, 2017*

**math**

Jim, Bob, Walk-Fast

*February 28, 2017*

**Intermediate Algebra**

copy/paste of special symbols doesn't work too well here. On the other hand, parentheses () and +-/* operators work just fine, as does the caret ^ for exponents, as in t^2. Not sure how "Ã¢â‚¬â€¹" appears to you, but it...

*February 28, 2017*

**Math**

? means the 1/2 power. As with any exponents, powers of powers multiply exponents. ?(3^5) = (3^5)^(1/2) = 3^(5/2) (?3)^5 = (3^(1/2))^5 = 3^(5/2) Now try your problems.

*February 28, 2017*

**Pre Calculus**

#1 There are two 8's, so while there are 6! permutations of the six digits, in any one of them, the two 8's can be swapped, and it's still the same arrangements. Same for the 5's. So, there are only 6!/(2!2!) = 180 distinguishable arrangements. The same caveat ...

*February 28, 2017*

**Enough Already!**

check your first post.

*February 28, 2017*

**Math**

the base has area ?(s(s-a)(s-b)(s-c)) where s = (a+b+c)/2 so the area of the base is ?(15.075(15.075-14.4)(15.075-8.25)(15.075-7.5)) = 22.936 so the volume is 22.936*2.1 = 48.1656 I suspect a typo somewhere. Or I misinterpreted the description.

*February 28, 2017*

**Algebra**

well, a = -15 and d = -8 now use the formula for the general term of an AP.

*February 28, 2017*

**math**

-14 <= t <= -3 or, |t+8.5| <= 5.5

*February 28, 2017*

**math**

how many ounces per pound? So, what is the cost of 1 ounce?

*February 28, 2017*

**Math**

y goes down 5 when x goes up 1, so start with y = -5x adjust that, since when x=0, y = -1.

*February 28, 2017*

**math**

$0.80/16 * 9

*February 28, 2017*

**Math grade 6**

first step: figure the volume of the blocks.

*February 28, 2017*

**maths**

what is 25% of 500? for each of 2 kids... for each of 12 months...

*February 28, 2017*

**math**

That's only 4 angles. You know they add up to 540°, so figure out the 5th angle, and add 'em up, solve for x.

*February 28, 2017*

**math**

if you can do 2/3 - 3/7 you can do this. Just place over a common denominator.

*February 28, 2017*

**calculus**

2?[0,1] 2/(x^2+1)-x^2 dx

*February 28, 2017*

**calculus**

If you sketch the region, it should be clear that dx is the way to go.

*February 28, 2017*

**calculus**

I would integrate along dy, since the boundary changes at x=1 That makes the integral easy: ?[2,5] (y^2/4 - (3-y)) dy If we integrate along dx, then we need ?[-2,1] 5-(3-x) dx + ?[1,25/4] 5-2?x dx

*February 28, 2017*

**Math**

None is true as things are written ?-27 = -3 and two complex roots ?81 = ±3 and two complex roots 3?-1000 = 30?-10 = 30?10 i 4?-16 = 4*4i = 16i

*February 28, 2017*

**Math**

yes, I'm sure someone does.

*February 28, 2017*

**Math**

well, 10^2 = 100 11^2 = 121 ...

*February 28, 2017*

**Math**

just add exponents. If it winds up negative, it's in the denominator. #3: (4^-1)(3^-1) = (4*3)^-1 = 12^-1 = 1/12

*February 28, 2017*

**Math**

well its 24 heavier/ lighter from riandrop to electron vice versa.... so its 24 orders of magnitude

*February 27, 2017*

**Algebra**

10^(-3) = 1/0.001 × 1 meter 1/0.001 = 1000

*February 27, 2017*

**Algebra**

if a slice of pizza is 1/8 of a pizza, how many slices are there in a whole pizza? an ant is 1/1000 as long as a human, so ...

*February 27, 2017*

**Calculus**

if the car has gone x miles, the distance z to the farmhouse is z^2 = x^2 + 36 so, find z(10) and then z dz/dt = x dx/dt and plug in your numbers.

*February 27, 2017*

**Calculus**

the shadow's length is changing at dx/dt. the tip of the shadow is moving at dy/dt + dx/dt

*February 27, 2017*

**Calc**

since |sinx| <= 1, 0 < sin^10(x) e^-x <= e^-x since ?e^-x dx converges so does this one.

*February 27, 2017*

**math**

1/8 * 12 = ?

*February 27, 2017*

**math**

8*(4/10) ft * 10*(4/10) ft = 12.8 ft^2

*February 27, 2017*

**Math**

rise/run = 1.5/12

*February 27, 2017*

**Pre Calculus 30**

think about it. For every combination of 3 letters (26^3), there are 900 ways to choose the following 3 digits.

*February 27, 2017*

**Pre Calculus 30**

1. ok 2. ok 3. 26^3 * 9*10^2

*February 27, 2017*

**math**

well 15 = 5*3, so she can make 3 * 2/3 gallons or, x/15 = (2/3)/5 = 2/15

*February 27, 2017*

**physics**

you have two sides (speed * time) and the included angle. So, use the law of cosines.

*February 27, 2017*

**alegebra**

(6060/100100)*299299 = 90597/5 = 18119.4 or, about 6/100 * 300300 = 18018

*February 27, 2017*

**Math**

11h+6

*February 27, 2017*

**Math**

55 + 0.08*225 = ?

*February 27, 2017*

**MATH**

well, 65 = 50+15, so ...

*February 27, 2017*

**Math**

600*0.80*1.20 = 576

*February 27, 2017*

**math neeeeed help plez help**

come on - corresponding sides are equal. Match up the letters in order. Hmmm. I suspect a typo.

*February 27, 2017*

**calculus**

so, do the math! what is dv/dx?

*February 27, 2017*

**calculus**

the volume v is v = x(7-2x)(11-2x) = 4x^3-36x+77x so, find x where dv/dx = 0

*February 27, 2017*

**Math**

multiply the numbers. add the exponents for each variable. Review your material on rules of exponents!

*February 27, 2017*

**Math**

?(16^2-4^2) = ?(256-16) = ?240 = 15.49 So, it is 15.5

*February 27, 2017*

**Math**

200 is not a perfect square! It is 2*10^2 7. READ THE QUESTION: How tall is the utility pole, to the nearest tenth? Not an integer! What calculation did you do?

*February 27, 2017*

**Math**

1. ok 2. if the number terminates as shown, then it is rational 3. 250 is not a perfect square. It is 10*5^2 5. ok 7. nope. 16 is not even the closest integer.

*February 27, 2017*

**Math 10**

9?2 = ?(81*2) 2?6 = ?(4*6) 8?3 = ?(64*3) 4?5 = ?(16*5) 6?2 = ?(36*2) I'll let you finish off.

*February 27, 2017*

**math**

I am shocked to see your first try. v(t) is a function. it is v of t, not v times t!

*February 27, 2017*

**SCIENCE**

KE gained = PE lost

*February 27, 2017*

**maths**

f(x) = (1+3x^2)^(1/3) / x f'(x) = ((1/3)(1+3x^2)^(-2/3) * 6x)(x) - (1+3x^2)^(1/3)(1) ---------------------------------------------------- x^2 -(x^2+1) ------------------------- x^2 (1+3x^2)^(2/3)

*February 27, 2017*

**Math geometry**

1) the base angles are equal, so (50-x)^6 = (30x-12)^6 50-x = 30x-12 ... Find x, evaluate the angles, and subtract them from 180 2) I assume you mean lengths. If they are b and B, 8(b+B)/2 = 52 3)The medians of a triangle meet 2/3 of the way from a vertex to the opposite side...

*February 27, 2017*

**physics**

horizontal distance or vertical distance? You need to provide a bit more context. For a nice discussion of any trajectory, see https://en.wikipedia.org/wiki/Trajectory

*February 27, 2017*

**math**

1:5 = 2:10

*February 27, 2017*

**Math**

h = 1/f h' = -1/f^2 f'

*February 27, 2017*

**Math**

the slope of the line is 1. So, you want the slope of the tangent to be 1. f'(x) = 6x^2-24x+19 = 1 x = 1,3 check: f(1) = 9 f(3) = 3 So the tangent lines are y-9 = x-1, or y=x+8 y-3 = x-3, or y=x the graphs are at http://www.wolframalpha.com/input/?i=plot+y%3D2x%5E3%E2%88%...

*February 27, 2017*

**Calc**

dy = (2x-7) dx so, ?x ? (2x-7) ?x

*February 26, 2017*

**Maths, triangle trigonometry**

draw a diagram. If the two lighthouses are at S and N, and the ship moved from A to B, then let the east-west distance moved by the ship be x. x = 5cos20° SN = x tan50° - x tan10°

*February 26, 2017*

**Maths, triangle trigonometry**

It's handy to think of P,R and Q as complex numbers, with P=(0,0). Find Q-R and then convert to polar form.

*February 26, 2017*

**Physics**

the horizontal speed is constant: 20 cos39° The vertical position is (20 sin39°)t - 4.9t^2 so, figure how long it takes to go 55m, then use that to get the relative height at that time.

*February 26, 2017*

**Physics**

If the height is h, then the vertical position y at time t is y = h - (9.4 sin21°)t - 4.9t^2 y(6) = 0, so you can find h. the horizontal speed is constant: 9.4 cos21° Now you can answer the questions.

*February 26, 2017*

**math**

First off, your distance is wrong. You must have used some bogus formula. d^2 = (5+3)^2 + (2+4)^2 = 100 d = 10 Since that is the distance from the center to a point on the circle, it is the radius. ...

*February 26, 2017*

**math NEED HELP ASAP**

add up the juice amounts: .65x + .90(150-x) = .75(150) ...

*February 26, 2017*

**math**

add up the vinegar in each part: .06x + .11(250-x) = .09(250) ...

*February 26, 2017*

**Math**

the coefficient of x^5 is negative. So, for x large negative, f(x) is large positive for x large positive, f(x) is large negative The lower powers don't matter for end behavior.

*February 26, 2017*

**math**

make a table for t=1 to 5. The annual cost is 1: 300-5 = 295 2: 300-10 = 290 3: 300-15 = 285 4: 300-20 = 280 5: 300-25 = 275 just add them up. Hmm. Maybe you just use t=5 for all 5 years. In that case, the annual cost is 275, so the total would be 5*275 = $1375 How did you ...

*February 26, 2017*

**Math**

recall that cos^2 x = (1+cos2x)/2 so, cos^4 x = (1+cos2x)^2/4 now cos^2 2x = (1+cos4x)/2 and so on. In the end, you get sin^8(x) = 1/128 (cos8x - 8cos6x + 28 cos4x - 56cos2x + 35)

*February 26, 2017*

**Pam**

x^2 is never less than zero, so f(x) is never less than -3. The vertex is at (0,-3) In general, f(x) = ax^2+bx+c has its vertex at x = -b/2a f(x) = a(x-h)^2 + k has its vertex at (h,k). In this case, h=0 and k = -3, so the vertex is at (0,-3)

*February 26, 2017*

**Pam**

The 3 is tiny, but the curve does not approach the line y=x. It gets arbitrarily close to the line y=x+3.

*February 26, 2017*

**Pam**

While the asymptote is a sloping line, and it looks like it ought to be x+11, it is not. (x^2+11x+16)/(x+8) = x+3 - 8/(x+8) So, the asymptote is actually the line y=x+3

*February 26, 2017*

**Pre-algebra**

If the cut is x inches, then the length and width are reduced by 2x, and the height is x. So the volume is v = x(40-2x)(20-2x) = 4x^3-120x^2+800x I can't believe that finding the maximum value of such a function is a topic for pre-algebra! It requires either analysis of a ...

*February 26, 2017*

**math**

?r^2h = 2800, so h = 2800/(?r^2) So, the cost function is c = 2*3?r^2 + 4*2?rh = 6?r^2 + 22400/r now just find r when dc/dr=0 and use that.

*February 26, 2017*

**@Ms algebra**

No "|" key on your keyboard, Ms?

*February 26, 2017*

**Algebra**

well, start with time = distance/speed

*February 26, 2017*

**math**

L(L-2) = 20

*February 26, 2017*

**math**

clearly, r = 2/5 now just use your formula.

*February 26, 2017*

**Maths**

If you meant to solve 18m^2-8m = 0 just factor out 2m: 2m(9m^2-4) = 0 2m(3m-2)(3m+2) = 0 your steps make no sense; you have discarded factors, changed signs, etc. Pay attention to what you're doing!

*February 26, 2017*

**maths**

find the angle between the headings (not bearings!) use the law of cosines for the third side.

*February 26, 2017*

**Maths**

sorry, that's n(n+1)/2 So, you have (n+1)(n+2)/2

*February 26, 2017*

**Maths**

I expect the differences are 3,4,5,6,7,... Did you know that 1+2+3+...+n = n(n-1)/2 ?

*February 26, 2017*

**MATH NEEDS HELP NOWw**

Did you take a look at the terms? 1, 1, 0, 0, ...

*February 26, 2017*

**maths**

consecutive angles add to 180. Looks to me like the two acute angles are 70° each.

*February 26, 2017*

**physics**

h(t) = 5t - 4.9t^2 max height at t=5/9.8 so, figure h at that value of t. Total distance is that height up, then back down.

*February 26, 2017*

**maths**

If you have a protractor, this should be easy.

*February 26, 2017*

**calculus**

arctan x = x - x^3/3 + x^5/5 - ... so, x-arctan(x) = x^3/3 - x^5/5 + x^7/7 - ... divide by x^3 and you get 1/3 - x^2/5 + x^5/7 - ... as x->0, that -> 1/3

*February 26, 2017*

**calculus**

surely you recognize the sequence 1, 3, 6, 10, ... as n(n+1)/2 it is the sequence of partial sums of 1+2+3+4+...

*February 26, 2017*

**Calculus**

a = xy da/dt = y dx/dt + x dy/dt d^2 = x^2+y^2 Now just plug in your numbers (I used x and y instead of w and l, since the l looks like a 1)

*February 25, 2017*

**Calculus**

xy = 12 y dx/dt + x dy/dt = 0 Now just plug in your numbers and solve for dy/dt

*February 25, 2017*

**Algebra 2**

Since the domain of ?x is x>=0, you will need (x-3) >= 0. That is, x >= 3. So, plug in some values of x and plot the points for y=-?(x-3): x y 3 0 4 -1 7 -2 12 -3 ... It will look like the bottom half of a horizontal parabola with vertex at (3,0). The equation could ...

*February 25, 2017*