# Posts by Steve

Total # Posts: 52,253

**@oops**

I see I can neither factor nor count. Go with Reiny.

**Maths**

7056 = 2 * 3528 = 2^2 * 1714 = 2^3 * 857 Now factor 857. You know there are no more 2's in there, so start with 3, and so on. So, what do you get? Since there are only three 2's, the square root will not be an integer, but will have a radical left over.

**Math - eh?**

Is that (a^q)-r or a^(q-r) etc. And is that comma supposed to be a period? That is, are the three items all to be multiplied together?

**math**

recall that (u-v)(u+v) = u^2-v^2 Now let u = 2?b v = ?(3a) and it falls right out

**geometry**

see related questions below

**math**

42

**Math**

don't know. some probably can do polar coordinates, but the implicit definition makes it tricky. They wouldn't look as nice as the online ones, that's for sure.

**Math**

first step: use real math notation (x^2+y^2-1)^3 = x^2 y^3 As with any function, just start plugging in values for x (or y) and solving to get the other coordinate. Not easy, in this case, since high powers are difficult to solve except in special cases. The other, easier, way...

**math**

not even close. That 25 in there doesn't just disappear...

**math**

(30*25*14)/42 = ?

**calculus**

I guess that would just be ?[-5,5]?[0,?(25-x^2)] y dy dx = 250/3

**maths**

the job is 12*6 = 72 man-hours of work. In 1 hour, the 12 men have done 1/6 of the work, leaving 60 man-hours to do. That will take 20 men 3 hours to finish up.

**math**

if you mean 16% is 832, then .16x = 832 ...

**Math**

hmmm. You need to review just what "isosceles" means ...

**math**

any situation where one quantity changes steadily. All you need are two pairs of data relating the items

**math**

the 25% + 2/9 of the remaining 75% add up to 1/4 + (2/9)(3/4) = 9/36 + 6/36 = 15/36 = 5/12 So, if he started out with x limes, then 7/12 x = 280 and so on

**math**

since the only difference is an ice cream, it clearly cost $10 That means that the cake was $200 ...

**algebra**

If you set up the curves as described, you have x^2/25^2 + y^2/20^2 = 1 x^2/125 - y^2/100 = 1 They intersect at (±25?5/3,±40/3) so pick P to be one of those points and figure your answer.

**algebra**

you need to review your material. The mode is the value which occurs most often. So, what do you think?

**math/econ**

recall that the elasticity is (dx/dp)(p/x) = (40)(p/(40(p-15^2)) = p/(p-15^2)

**Maths**

cubics are not easily done in general, but a little synthetic division should quickly show you that you have (x-1)(x^2-6x+5) and that is easy...

**science**

all of them, I guess ...

**Math**

We can assume that Lisa has 3 and Betty has 5, so (3-1)/(5+1) = 2/6 = 1/3

**Arithmatic Progression**

why post it twice? Using your formulas, you see that 5/2 (2a+4d) = 40 a+6d = 4(a+d) Now you can find a and d, and thus the sum of the 2nd five terms is the sum of the first 10, less the sum of the first 5: 10/2 (2a+9d) - 40

**Statistics**

you can play around with Z table stuff here: http://davidmlane.com/hyperstat/z_table.html

**Maths**

clearly, the fastest has run one complete lap, while the slowest has run only 1/4 of a lap. Then if they started at the eastern side of the track, after 30 seconds they are at the points E,S,W,N in order of speed, fastest to slowest. After 30 more seconds, they are at E,W,E,W ...

**maths**

well, there were 1100-220=880 mangos, so ...

**Calculus 2 - Indeterminate forms**

it's quite simple. The rule states that lim f(x)/g(x) = lim f'(x)/g'(x) so, your limit is the same as (ln2*2^x-ln3*3^x)/-sinx(x) now, as x->0, that -> (ln2 - ln3)/0 = ? This is confirmed by the graph at http://www.wolframalpha.com/input/?i=(2%5Ex-3%5Ex)%2F(...

**Geometry**

the original block has surface 6*2^2 subtract the two circles removed: 2*?r^2 add the curved surface of the hole: 2?rh where r = 1/2 and h=2 the volume is of course 2^3 - ?r^2h

**pre calc**

draw a diagram. You can see that 5/x = sin ?/3

**Pre-Calculus**

Since profit is revenue less cost, we have p(x) = 150x - (0.02x^2 + 100x + 3000) now just find the vertex of that parabola.

**Calculus**

If the base has dimensions x and 2x, then we have 2x^2y = 10 so, y = 5/x^2 So, the cost of the container is c(x) = 12*2x^2 + 5*2xy + 5*xy = 24x^2 + 15xy = 24x^2 + 75/x so, find c(x) when dc/dx=0

**pharm**

15 mg/ml * 120ml = 1800 mg

**Physics**

You can easily adapt the example here to fit your problem: http://physics.bu.edu/~redner/211-sp06/class13/class13_rotation.html

**math**

9+x

**Math**

still the same: https://www.jiskha.com/display.cgi?id=1500466804

**algebra**

If your Revenue equation is corrected to read Revenue(x) = 5x then your Profit equation is correct. Not sure about the "need to make" clause. It's just what she makes.

**maths**

that's better

**maths**

That's not what I get. Where's your work? Did you try actually using your results to see whether they produce the desired AP?

**Math**

subtract the inner park from the total area: (350+2w)(200+2w)-350*200 = 74464

**Mathematics**

You got me. Aside from expanding into Taylor series and dividing, I don't come up with a trick to evaluate it.

**Math**

since all the sides are equal, the perimeter is just 3 times the length of one side.

**Physice - oops**

I should have said dynes, not ergs. Ergs are energy, not force.

**Physics**

Recall that F = ma so, just multiply. Note that the answer will be in ergs, not Joules.

**math**

homework is 2/3, so revision is 1/3 1/3 * 9/2 = ?

**math**

well, there are 360 degrees in the whole pie, so ...

**math**

well, 1/5 of 35 is 7, so ...

**arithmetic progression**

8/2 (2a+7d) = 56 20/2 (2a+19d) = 260 ...

**geometric progression**

probably best to first fins a and d: a+4d = 8 a+9d = -7 now subtract, and crank it out.

**Math**

If the mother is twice as old in x years, then we have 45+x = 2(12+x)

**Math**

(-6/7+18/28)*-7/5 = (-24/28+18/28) * -7/5 = -6/28 * -7/5 ...

**Mathematics**

b/g = 3/4 (b-3)/g = 5/8 b+g = 42

**Math**

well, we do know that (1+.035)^10 = 1.4106 (1+.035/4)^(4*10) = 1.4169 ... e^.035 = 1.4191

**geometry**

h/27 = sin 47°

**Math**

a*-1/27=1/18 a=-7/6 Bzzzt. a = -3/2

**maths**

80*3 = 60*4 = 240

**Physics**

draw a diagram of the velocities. Recognize an 8-15-17 right triangle?

**Math**

No one asked how many fruits there are. You just need to give the fraction. Read the question carefully.

**Math**

3/5 + 1/4 = 12/20 + 5/20 = 17/20 so, what do you think?

**Calculus - incomplete**

What does the coastline look like? Is it straight? N-S, E-W? All I know for sure just now is that the radar station lies somewhere on a circle of radius 1.5 with its center at the port. Anyway, draw a diagram. It should be clear how to use the available angles and distances to...

**math**

No way to tell. However, if the function has rational coefficients, then the irrational roots must occur in conjugate pairs. Thus, the other root must be 3-2?2

**college algebra**

Let x = amount in bonds Then 68000-x is the amount in CDs Now just add up the interest: .08x + .07(68000-x) + .10*68000 = 12040

**Science**

total energy = PE + KE = mgh + 1/2 mv^2 Now just plug in your numbers

**math**

8 is 16% of the 50 sampled. That means that 200 is 16% of the whole population. 0.16p = 200 ...

**Quadratic Equation - Henry**

max height reached at t=2 h=0 at t=5 so, 2 seconds rising, 3 seconds falling he got the 3 by seeing how long it takes to fall 144 ft. s = 1/2 at^2

**Math**

Certainly not English -- the units are metric! To get the width of the path, subtract the inner garden area from the total: 40*25 - (40-2w)(25-2w) = 126

**Calculus**

the derivative is -x/50 + 50 maximum revenue occurs when that is zero.

**Chemistry**

what don't you understand? Surely you can at least pick out the elements, and then see which are atoms and which are molecules. And take a stab at the compounds; the ionic ones usually involve a metal and a halogen.

**AOOOGAH!! Homework Dump!!**

no ideas on any of these? We're not here to do your homework for you...

**Physics**

a = 2 m/s^2 means that v grows by 2 m/s every second. So, what do you think? v = at

**algebra**

recall that the vertex of a parabola ax^2+bx+c is at x = -b/2a

**Algebra**

g(x) is written in the slope-intercept form. Its slope and y-intercept should be obvious. For f(x), note that y changes by 2 when x changes by 1 f(0) = -1 ...

**decreased by twice a number**

if the number is x, what is twice the number? 2x what is 6 decreased by 3? 6-3 so, what do you think?

**Algebra**

each element must be identical in the two matrices (you already have 1=1 and 3=3), so you just have to solve 5x-8 = 2 4m-1 = 7m+6 then use those values to fill in the unknown elements.

**Calculus**

you have a point and a slope, so just use the point-slope form, which you learned in Algebra I: y+4 = 5(x-2)

**algebra**

?121 = ?

**math**

0.7x = 3.43 x = 3.43/0.7 = 4.9

**math**

4/100 x = 0.8 x = 0.8 * 100/4

**maths**

10/2 (2a+9d) = 220 5/2 (2a+4*2d) = 100

**Maths**

1,2,4,7 cannot be made I think you can easily show that all the rest are multiples of 3 or 5, or can be made using them and makeable remainders.

**KSU**

7:3

**Math**

take logs. 100 log 99 = 199.56 99 log 100 = 99*2 = 198

**algebra**

Add up the wages: 8x + 11(23-x) = 208

**One-to-one function**

think about it. If f(1) = 2 and f(2) = 2 how can you pick an inverse g(2)?

**Calculus**

now you have given even less information than in your last post! There are many many functions passing through (4,-11) tangent to that line. The simplest is, of course, f(x) = (7x-61)/3 Even the next simplest one could be a parabola opening either up or down, and there are ...

**math**

man, I can't even figure out the question...

**Quadratic Equation**

well, you have the function. Using it, you can find the initial speed (64 ft/s), maximum height (at the vertex), and how long it takes to hit the ground (when h=0). Incidentally, it is odd that the initial height is given in meters, but the -16t^2 is in ft/s^2.

**Calculus**

No way to tell, unless you know you are working with something simple, like a quadratic. If y = ax^2+bx+c and you have two points, then you also have 2ax+b = slope of the tangent line Then you have three equations to solve for a,b,c.

**Pre-Calc**

there are lots of online graphing sites, like desmos, wolframalpha, etc. Find one you like and produce your graphs; see where they intersect.

**Math**

(2x 3 y2 3z)(3xyz^4)^3 = (18xy^2z)(27x^3y^3z^12) = 486x^4y^5z^13 (2x^3y^2 3z)(3xyz^4)^3 = 162x^6y^5z^13 Or something else, depending on how you have mangled the expression

**Math**

(-2y4^z3)^2(-xy)^4 = (4y^8z^6)(x^4y^4) = 4x^4y^12z^6

**Physics**

(0,-6)+(10,0)+(0,5) = (10,-1) I assume you can find vector lengths. The distance, naturally, is just 6+10+5

**Chemistry**

assuming that is the number of molecules of CO2, then just divide by Avogadro's number: 7.7x10^24 / 6.02x10^23 = 1.28x10^1 = 12.8 moles

**physics**

1.2x10^-6 / 0.25x10^-12 = 4.8x10^6

**Math**

I will try to unravel your garbled language, and get x^2 = 100/2 + 12+1 If that's not right, maybe you can fix it up. Not quite sure what "dozen one" means.

**Easy Math**

f(x) = 1/x g(x) = x^2-5 f?g = f(g) = 1/g ...

**Math trigonometry**

Assuming you meant 8sin^2?+10 sin? cos?+3cos^2? = 0 (2sin?+cos?)(4sin?+3cos?) = 0 see what you can do with that.

**Calculus**

we have ?/3 h^2(3r-h) = 5?/3 3rh^2-h^3 = 5 3h^2 dr/dh + 6rh - 3h^2 = 0 h dr/dh + 2r - h = 0 dr/dh = (h-2r)/h = 1 - 2r/h ...

**MATHS**

13601 = 87*156 + 29

**science**

If there are g grams of gold, then add up the volumes (mass/density): g/19.3 + (9.35-g)/10.5 = 0.690 g = 4.6 So, the % mass of gold is 4.62/9.35 = 0.49 = 49%