# Posts by STEVE

Total # Posts: 54,287

English
"The number of souls in Ireland being usually reckoned one million and a half, of these I calculate there may be about two hundred thousand couples whose wives are breeders, from which number I subtract thirty thousand couples, who are able to maintain their own children...

English
Thank you

English
Read this excerpt from Alexander Pope's The Rape of Lock "No common weapons in their hands are found/ Like gods they fight l, nor dead a mortal wound.../ See, fierce Belinda on the Baron flies/ With more than usual lightning in her eyes..." This account of the ...

Chemistry
note that each molecule (or mole) of O2 produces two molecules (or moles) of H2O

Chemistry
Balance the equation: 2H2+O2 = 2H2O So, you have half as many moles of O2 as of H2 So, 1/2 the volume.

Physics
just plug in your numbers for the formula for a trajectory. The height y = 1.2 + (tan26°)x - 4.9/(40.4 cos26°)^2 x^2 is y(127) >= 3.5?

math
3.25 * (5 5/6) = 13/4 * 35/6 = 455/24 = \$18.96

English
correct (all the others are not even verbs)

pre calculus- math
e^.12t = 3

Algebra I
Huh? There's nothing to solve. Just evaluate the numbers... ½ (900kg)*(20m/s)^2 = ½(900)(20)^2(kg)(m/s)^2 = (450*400) kg-m^2/s^2 = 180000 N-m = 180KJ

Chemistry
Since the force is the same, the height will be inversely proportional to the densities (because the cross-section has the same area) -- think about it: half as dense (half as much mass), twice as high. So, if H is the height of mercury, the height h of iodide obeys h = (13.6/...

math
Looks like 3 to me: HHHHHTTTTT HHHHHHHHTT HHHHHHTTHT HHHHHHHHHH

Math
no idea. what does R have to do with u and r? Is R=r' ? If so, then #1: R = r' = u-r = {2,4,6,...} #2 u-r = {...-4,-2,0,2,4,...}

Algebra 2
huh? Does no one see that "ln" there? ln(x-4) < 6 since e^x is increasing, a<b ==> e^a < e^b x-4 < e^6 x < 4+e^6

Math
You want to get the variable all by itself. So, if you have 2x, you want to divide by 2, since 2/2 = 1, and that leaves you with 1x, or just x. -13x=-65 x = -65/-13 x = 5 multiply by 7, since 7/7=1 r/7=-8 r = -8*7 r = -56 add 10, so b is left alone: b-10=-14 b = -14+10 b = -4 ...

Math
so try posting a few problems you can't solve. Also, google is your friend. Looks for examples of your key topics.

Math - eh?
If this is reverse Polish notation, there are too many operators...

Math
since x = y+9, you want the maximum value of (y+9)y^2 = y^3+9y^2 Not sure what tools you have for finding the maximum, but a quick derivative will show that it is at x = 3 y = -6

Math
just multiply the coordinates by the scale factor!

Math 7a
3a - 4 <= 5 3a <= 9 a <= 3 do the same steps you use to solve an equation

Math 7a
wow - what a lot of text and bad formatting and non-standard font use! n/-3 + 5 > 4 n/-3 > -1 n < 3

Math
draw a dashed line at y=2 shade the region above it

math
4/15 + x + 3/5 = 1 4/15 + x + 9/14 = 15/15 ...

Human Kindness
You cannot. You can only encourage them.

Math 8th Grade Pre Algebra
5h - 9 = -16 + 6h subtract 5h from both sides add 16 to both sides now what do you get?

Math
perfect vision!

Math - eh?
you have mismatched brackets what are the spaces supposed to mean? "2f 3 -14 3" makes no sense and there's no "=" sign to make an equation. Geez - check what you write, willya?

physics
PV=kT, so you want (1.02*10^5)(.00661^3) = P(.00650^3) P = 1.07*10^5

Math
so, start with the smallest 3 primes: 2*3*5=30 So, any multiple of 30 can be divided by those three primes. Try using other primes, and see what you think ...

Math
recall the properties of multiplication (-w)(-10w^3) = (-w)(-10)(w^3) = (-1)(w)(-10)(w^3) = (-1)(-10)(w)(w^3) = 10w^4

Calculus
the slope of 3f^2 is 6f f' = 6*5*7=210 So far, so good. 3f^2(3) = 3*5^2 = 75 So, you want the line through (3,75) with slope=210 y-75 = 210(x-3) your surmise is correct

Math
L = F/2 - 5 F = 2(L+5) L + 2(L+5) = 79 Lindsey is 23 and her father is 56

math
2/3 < x/5 < 6/7 10/3 < x < 30/7 3.3 < x < 4.3 Looks like x=4

math
y=m is a horizontal line x=n is a vertical line y=x is a sloping line (a) perpendicular (b) neither

MATH
|x+3| ... shift left 3 -|x+3| ... reflect over x-axis -|x+3|-2 ... shift down 2

PreCalculus
I got my answer from the graphs of the functions: http://www.wolframalpha.com/input/?i=-5e%5E(-4x%2B2)+%2B3%3D+1%2F2+log(1%2Bx%5E2) What I don't understand is how you can evaluate log(sqrt[x^2+1]) without knowing x ... I think when they said to use your calculator, they ...

PreCalculus
Hmmm. I get 0.642538 I'm confused on how you got 1/2 log(1+x^2) = .707486674 in any base, since you don't know x.

Direct Variations
y/x = 10.4/4 = 2.6 y = 2.6x Geez! 3.4*4 = 13.6 Maybe you could show your work, so we can see where you are taking a wrong turn. Or are you just guessing so we'll think you tried?

Algebra
Hmmm (2/3)*3 = 2, not 7 y/x = (7 1/2)/3 = (15/2)/3 = 15/6 = 5/2 y = 5/2 x You need to learn to check your answers. At least do a sanity check. 2/3x < x, so how could y = 2/3 x relate 3 and 7?

Math
(a) just substitute 25 for P (b) solve 50(P-2) = 800

math
Is this a continued fraction? If not, do you mean what you typed? 2?3 + 9÷?3 + 12÷?3 ... = ?3 (2+3+...+10) I'm sure you can add up an arithmetic sequence, right?

Math
Each year she gets 3.5% or 0.035 time the amount invested. So, after 3 years, that's 4500 * 0.035 * 3 Review your formula: I = Prt, right?

Computer
i=0 while (i>=0) { read i,j print i,j } Not sure whether "in order" means in the order given, or smallest first. If you need to sort them, I'm sure you can fill in the missing step. You also say you want 2 numbers, then talk about the "trio." ??? ...

math 7/8 grd
I don't like that subtraction. Subtracting a larger value gives a smaller result. For example, suppose we have small x > 0 d = -7+x > -7 d+s = -7+x+s > -3 x+s > 4 s > 4-x So, suppose x = .1, and thus d = -7+.1 = -6.9 If s > 4-.1 = 3.9, ok, since d+s >...

Pre algebra
Hard to tell just what you meant, but just adding what you wrote (assuming all dimensions are in cm), then p = 8 + 9x + 9 + 9x = 16+18x ...

Mathematics
(a) P(x,y) = 31(20-x)+74(10-y) (b) P(9,4) = 31(20-9)+74(10-4)

geometry
If the 2nd circle's line is a diameter of 14, then its area is done the same way: pi*7^2 = 49pi By the way, if the diameter is 25, the radius is 12.5, not 12. Unless you can tell more about the line and its relation to the 2nd circle, I can't figure out what it is you ...

algebra
|x+3| ... shift left 3 -|x+3| ... reflect over x-axis -|x+3|-2 ... shift down 2

Math helppp
Just use the sum-to-product formulas... sin(a)-sin(b) = 2cos((a+b)/2)sin((a-b)/2) cos(a)-cos(b) = -2sin((a+b)/2)sin((a-b)/2) So, let a=8? b=10? and you have sin(8?)-sin(10?) = 2cos(9?)sin(-?) cos(10?)-cos(8?) = -2sin(9?)sin(?) now it is clear to see that 2cos(9?)sin(-?) = cot(...

physics
see your previous post

calculus for economics
revenue = price * quantity break-even is when revenue = cost

Math
clearly the 4.3m ladder must span the 1.6m distance. Its height is thus h = ?(4.3^2-1.6^2) So, the length of the other ladder must be ?(h^2+5^2) = ?(4.3^2-1.6^2+5^2) = 6.4

physics
3*10^5cm * 1rev/(65? cm) = ? rev

algebra 1
25 times the cost of sending one message ...

Maths
103 12/37 tsp.

Math Unit 3
geez - you have the proof. Just fill in the blanks.

Algebra
since time = distance/speed, if the turtle's speed is x m/min, then since .5 m/hr = 1/120 m/min 21/x = 8 + 21/(x+1/120) + 4 The turtle moves at 7/60 m/min = 7 m/hr The hare moves at 1/8 m/min = 7.5 m/hr you can check the times to verify that they work out.

Math/calculus
use your sun-to-product formulas, and this drops right out.

Math helppp
wolframalpha is your friend. See http://www.wolframalpha.com/input/?i=3cos+(4pix+-pi%2F2)+-2 f(x) = 3cos(4pi(x - 1/8) -2 So, it is just the graph of cos(x) shrunk horizontally by a factor of 4pi shifted right by 1/8 stretched vertically by 3 shifted down 2

Calculus
It appears so. y and z are functions of t, so you need the quotient rule.

Precalc
You want f(±?) = +? This is impossible, since there is a horizontal asymptote at y=0. hole and vertical asymptote: (x-1) / (x-4)(x-1) This also gives y=0 as the vertical asymptote, since the denominator has higher degree than the numerator. not sure what has the ...

math
No, the % increase is the change divided by the original amount: 880/1195 = 0.736 = 73.6% check: 1195 * 1.736 = 2075 and besides, 880/100 = 8.8 = 8800% consider. 6 is 50% more than 4, because 6-4=2 and 2/4 = 0.50 = 50% 4 * 1.50 = 6

Linear Equation
2x + x/2 = 20

Math
x+y-z= 6 2x-y +z=-9 X-2y+3z=1 using substitution, you can do: from #3, x = 2y-3z+1 Using that in #1 and #2, you get (2y-3z+1)+y-z = 6 2(2y-3z+1)-y+z = -9 3y-4z = 5 3y-5z = -11 Now, using 3y=4z+5, (4z+5)-5z = -11 -z = -16 z = 16 3y = 4*16+5 = 69, so y = 23 x = 2*23-3*16+1 = -1 ...

geometry
42

maths
42

math
I assume you mean ?(x+10) + ?(x-17) = 9 ?(x+10) = 9-?(x-17) x+10 = 81-18?(x-17)+x-17 18?(x-17) = 54 ?(x-17) = 3 x-17 = 9 x = 26 check: ?(26+10)+?(26-17) = ?36+?9 = 6+3 = 9 nope

Trigonometry
since sin(?/6) = 1/2 and sine is negative in QII and QIV, 2x = 7?/6 or 11?/6 + 2n? x = 7?/12 + n? or 11?/12 + n?

Math
j = m+4 = 8+d mp = 16+jd clearly, Jack is not a twin with either Mark or David. So, Paul is one of the twins. Either p=j or p=m or p=d See what you can do with that. You now will have three equations in three variables, after getting rid of p.

Maths
know what? Check what you wrote and turn it into something useful ...

Math
(3/10 in) / (7/8 mi) = (3/10) / (7/8) in/mi = 3/10 * 8/7 in/mi = 24/70 = 12/35 in/mi

Math Help
b(ab) = b*a*b = a*b*b = ab^2

Chemistry
how many moles of H2O in 135L (at 18g/mole)? half that many moles of H2SO4 Now use Avogadro's Number to find # molecules.

Maths
suppose you change the numbers to make the method easier? How much do you need to subtract from 12 to make 3? 12-3 = 9 so 12-9 = 3 get it?

John
well, if you meant 2x^4-3x^3-7x^2+12x-4, it is a quartic, but can easily be factored into two quadratic factors. It is (x^2-4)(2x^2-3x+1) which are both easily solved.

John
not a quadratic. A cubic. There are no rational roots, so what techniques do you have for solving polynomials?

Maths
depends on the total distance.

maths
3:1 means 4 parts 12/4 = 3 3*3:3*1 = 9:3 do the other in like wise.

Algebra
50 by 25 As with all such problems, the maximum area is when the fence is divided equally among lengths and widths. x+2y = 100 area = xy = x(100-2x) now just find the vertex of that parabola.

Algebra
(a) find t when h=0 (just solve for t, as usual) as with all quadratics, the vertex is midway between the roots, at t = -b/2a = -64/-32 = 2

Math PLz Help
just double all the numbers! So, if (vwxy) = 2(VWXY), v = (12,4) and so on

Calculus
extreme where y' = 0 decreasing where y' < 0 y' = (3x-2)(x-2) so, it should be clear where y'=0. y' < 0 between the roots. Easily verify your results using the graph at http://www.wolframalpha.com/input/?i=x(x-2)%5E2

Math
2 1/4 + 1 3/4 = 4 1/3 + 1 1/3 + 4 1/3 = 6 4+6=10, so just add up the mixed numbers.

Math PLz Help
just multiply all the coordinates by 2!

math
1C ...

math
The centroid divides each median into two parts, in the ratio 2:1. So, CP = 2*PD 2(4x-3) = 30 ...

math
cool. Now what? And you can use the character ? for triangles, instead of whatever unicode symbol you tried.

math
150/200 = 3/4 = .75 = 75%

Math
compound: P(1 + 15/2)^3 = 3920 simple: P(1 + 15/2 * 3) = 3920

Math, algebra
well, the set 7.5, 7.5, 8.5, 8.5 fits the bill for 4 numbers. See whether you can expand that to 8 values.

Math
just solve h=0

Math
just solve -16t^2 + 4t + 442 = 430 Your equation, with -4t, has the stone being thrown downward. It seems to be at odds with the skyward initial toss.

Math
78 = 2x39 = 2x3x13

Math
100 = 10^2 = 2^2 5^2 while D is correct, it is not the prime factorization B should be 2x2x5x5

Calculus
oh, yeah. My equation was wrong anyway, as it should have been ((15-x)/4)^2 + (x/3)^2*?3/4

Calculus
glad you got rid of all those pesky fractions! :-)

Calculus
The triangle's perimeter is x, and the square's is 15-x. So, the area is ((15-x)/4)^2 + x^2*?3/4 Now do with that what you will.

Math
well, P(BW) = 5/11 * 3/8 P(WW) = 6/11 * 4/8 so, what does hat tell you?

Science HELP
Well, Death Valley is in California the Gobi is in Asia the Caribbean is a sea, not a desert. so, what do you think? Ever hear of google?