# Posts by STEVE

Total # Posts: 51,209

**math**

I assume you meant that each coin is 1/8 inch thick. Recall that the surface area of a cylinder is a = 2?r^2 + 2?rh = 2?r(r+h) Now just plug in your numbers.

**math**

you might start here. Make a flowchart that reflects the logic of the code. http://www.jiskha.com/display.cgi?id=1495379575

**Math**

Let's start with Physics and Chemistry. at most 30% passed physics at most 28% passed chemistry so, at most 58% passed either of the two subjects. That is, the % who failed both is at least 42% That is 100-(30+28)% Now extend that to the other subjects.

**Math**

x/8 + 14 = x

**Math**

clearly a negative answer makes no sense. How did you arrive at your result?

**Math**

just like the goldfish problem. What do you think?

**Math**

suppose you divide a pound of tea in halves. How many are there?

**Math**

ok. how many half-pound pkgs in a whole pound? Multiply that by 2 1/2

**maths**

6.25^(1/2) = 2.5 2.5^3 = 15.625 or, using fractions, 6.25 = 25/5 (25/4)^(3/2) = 125/8

**Math**

Surely you can see that there is something missing where you say one this of the remainder earn salaries between 15000 and 18000 how much is "one this" ?? Do you not read what you post?

**Math**

this is just like the goldfish problem. What do you think? Of course, it will help if you fix the missing information...

**Math**

1 - 1/5 - (4/5)(3/8) = 1/2

**Calculus**

Hmmm. The y-axis does not form part of the boundary. Each square of thickness dx has a base that is y=x^2-1 in width. So, adding up all the squares, the volume v is ?[1,2] (x^2-1)^2 dx = 38/15

**Chemistry**

25ml of 1.0M contains 0.025 moles of solute. So, how many grams is that for this compound?

**math**

xy = k now just plug in your numbers.

**math**

45:9000 = 1:200

**math**

?u is real only for positive u. So, that means ?(x+4) is real only for positive values of x+4: x+4 >= 0 x >= -4

**Calculus**

#1

**Math**

Interesting article, but since when does ?72 = 2.913 ?? 2.913 = ??72

**Pre-Algebra**

since the only two factors are 7 and 73, I'm not sure what is going on here.

**math**

just simplify 1 - 1/(p+1)

**Maths**

use the law of cosines. AC^2 = 300^2 + 200^2 - 2*300*200 cos 33° AC = 171

**Math**

since multiplication is commutative, just shuffle things around a bit. (-4x)(9x^2) -4 * x * 9 * x^2 -4*9 * x*x^2 -36x^3 PS -- it helps if you don't use "x" for both multiplication and a variable name.

**Calculus**

since -x^3 < -x on (-1,0), you should be subtracting (-x)-(-x^3). the actual math should be -(-3/4) - (-(-3/4)^3) = 3/4 - 27/64 = 21/64 and so on. It comes out the same. Assuming your intermediate results are good, the answer looks good.

**math**

huh? If P(7) = 1/7 then P(~7) must be 6/7 Not having a description of the spinner, it's hard to say much more than that.

**algebra**

combining like terms, m^2 + (-1+1)m + (-4-5) m^2 - 9 I suspect a typo somewhere above

**math**

she walks on a heading, not a bearing (3,0)+(2.35,4.41) = (5.35,4.41) so, the distance AC is ?(5.35^2+4.41^2) = 6.93 bearing to C is E39.5°N or, 50.5°

**math**

Let the acreage be x: corn y: soy z: oats x+y+z = 1200 20x+50y+12z = 40000 with your solutions, then evaluate revenue = 100x+300y+80z

**One more question Calculus**

You want the integral to be something of the form ?[a,b] f(x) dx Now that (2/n) at the end indicates that we are dividing 2 into n parts, so we will have ?[0,2] f(x) dx Now we see that k*2/n inside the sum, so that is the value of x at each of the interval divisions, so I ...

**Please help Calculus**

The curves intersect at (0,0) and (2,2) So, using shells of thickness dx, v = ?[0,2] 2?rh dx where r=5-x and h=x-x^2/2 v = ?[0,2] 2?(5-x)(x-x^2/2) dx = 16?/3 using discs (washers) of thickness dy, v = ?[0,2] ?(R^2-r^2) dy where R=5-y and r=5-?(2y) v = ?[0,2] ?((5-y)^2-(5-?(2y...

**Calculus Please Help**

The curves intersect at (-1,-2) and (5,4) Horizontal strips of width dy are the best here, so A = ?[-2,4] (y+1)-(y^2-6)/2 dy = 18 Using vertical strips is a bit trickier, because the boundary changes at x = -1 A = ?[-3,-1] ?(2x+6) - (-?(2x+6)) dx + ?[-1,5] ?(2x+6)-(x-1) dx = ...

**Calculus Please Check my answer**

I assume you meant d/dx ?[2,x^4] tan(t^2) dt = tan((x^4)^2) * 4x^3 = 4x^3 tan(x^8)

**Math**

start with trying to do multiplication with Roman numerals!

**physics relativity**

just use the Lorentz contraction factor

**math**

1 - 1/(p+1) = (p+1-1)/(p+1) = p/(p+1)

**maths**

so, use Pythagoras rule. c^2 = a^2+b^2 You have a and b, so just plug and chug.

**Calculus**

well, it is clear that cosx^2/(1+x^2) <= 1/(1+x^2)

**algebra**

huh? Just plug in the numbers for n: A(2) = 4+(2-1)(8) = 4+1*8 = 4+8 = 12 and similarly for any other values of n.

**math**

ax^2 grows faster than kx for any a and k you choose. or, equivalently, if a > b, x^a grows faster than x^b

**math**

factor the trinomial. It is a perfect square.

**Math**

ok, you have your cosine function correct, so you just need to solve 16.5cos 72t +29 = 32 16.5 cos 72t = 3 cos 72t = 2/11 72t = 79.52 + k*360 or 72t = 360-79.52 + k*360 t = 1.10, 3.89, 6.10, 8.89

**math**

the scale ratio is 4:10 = 2:5, so the area ratio is 4:25. 112 * 25/4 = ?

**Math**

(11(1/8)mi)/(3 1/2 min) = (11/8)/(7/2) = 11/8 * 2/7 = 11/28 mi/min

**Algebra**

x and x^2 are different animals you cannot combine x and y, either, or apples and oranges. If x is a dimension, like length, then x^2 is an area. They don't combine at all.

**Maths**

w = 7s w+5 = 5(s+5) ...

**math-precalculus**

since the period of sin(17x) is 360/17, there are 17 more pairs of solutions for x in [0,360) such that 17x = 180.34 + n*360 for n=0..17 17x = 359.66 + n*360

**Math**

A: y = 1.50x B: y = .013^(x-1) Now you can answer the questions...

**Algebra 1**

10 marbles total, so P(red,green) = 5/10 * 2/9

**math**

If the sides are x and y, then we have xy = 36 y = 36/x So, let x=4. Then y = 36/4 = 9 Now, you know that dividing by a larger value gives a smaller quotient. So, x>4 means y<9

**math**

900 * 0.9 * 1.1 = 891 so, a loss of $9

**math**

huh? Just solve -6t^2 + 43t = 77

**Math for IT**

you could start here: http://www.jiskha.com/display.cgi?id=1495379575

**maths**

not sure what c is, but any product involving a zero produces a zero result.

**physics**

v^2 = 2as convert km/h to m/s and plug in the numbers to find s.

**maths**

a) 1 - 2/5 = 3/5 who do not wear specs b) 16 = 2/5 x x = 16 * 5/2 = 40

**Precal**

There are 5C3+5C4+5C5 ways to choose the coins. Now, are there any sums which can be made in more than one way? If so, then they'd be counted twice.

**Math**

-100 + 56 = -44 Mark it off on the number line

**Math**

42 - (-20) = 62

**Calculus**

Since all the answers use f'(x^2), I assume that you meant k(x) = f(x^2) k'(x) = f'(x^2)*2x k"(x) = f"(x^2)*2x*2x + 2f'(x^2) So, (d) check an example, such as k(x) = sin(x^2)

**Math**

that's "difference" not "deference" 58-(-88) = 146

**physics**

if it takes t seconds after the cop gets going, then 20(t+1) = (1/2)(2)t^2

**Geometry**

coin outcomes are 1/2 each If the spinner has n areas, then each has a 1/n chance of being hit So, P(H,C) = 1/2 * 1/n

**Math**

so, plug in your numbers ...

**Math**

surely you can think of two factors of 28. Do they differ by 3?

**Math**

surely you have the formula for the future value of such a cash stream. If not, here's a site with the formula and a calculator. http://keisan.casio.com/exec/system/1234231998

**6th grade Math**

(0*1+1*2+2*5+3*3+4*6+5*7+6*9)/(1+2+5+3+6+7+9) = 4.06 ? 4.1

**math**

and that's pi, not pie!

**Math (Calculus II) (Volume Revolution Setup)**

Yes, if you rotated about x = -6, r=x+6. As you say, using shells of thickness dx, v = ?[1,4] 2?(5-x)(?x-1) dx = 103?/15 You can check your answer by using discs (washers) of thickness dy. In this case, v = ?[1,2] ?(R^2-r^2) dy where R=(5-x)=(5-y^2) and r=1 v = ?[1,2] ?((5-y^2...

**math**

(a) yes, since 40+40+100 = 180 (b) no, since c^2 = a^2+b^2 (c) yes. Use 9 for the base. The other two sides sum to 10, so to make them fit, you have to lift up the vertex to form a triangle.

**Maths-Complex numbers**

we know that |z+2| <= |z|+|2| = 1+2 = 3 use similar logic on the other side.

**maths**

481, naturally but somehow I don't think that's what you really wanted to ask ...

**Math**

(x-48)/x < -8 You cannot just multiply by x as shown above, because x might be negative, which would then reverse the direction of the inequality. If x > 0, then x-48 < -8x 9x < 48 x < 48/9 so, 0 < x < 48/9 If x < 0, then x-48 > -8x 9x > 48 x >...

**MATHS**

you could start here: http://www.jiskha.com/display.cgi?id=1495379575

**math-precalculus**

well, you have sec 2? = 3 cos 2? = 1/3 2? = 1.231 or 2?-1.231 so, divide those by 2, and then add ? to get all 4 solutions.

**Mathematics - Limits**

Hmmm. Using L'hospitals rule, we have the value as (a - 1/2 (1+x)^(-1/2))/2x (1/4 (1+x)^(-3/2)/2 -> 1/8 So, I don't see how we can assign a value to a, because the limit is 1/8 for any value of a. Am I missing something?

**Algebra**

A = 30 + 0.10m B = 50 + 0.05m see what you can do with those equations.

**Physics**

recall that v^2 = 2as = 2E/m a = F/m so, s=2

**Math**

Type in your function here, and it will give you the roots and other info. http://www.wolframalpha.com/input/?i=-0.4x%5E2%2B8.3x%2B4.3 On this one, x^2+3x-10 = 0 you should have factored it: (x+5)(x-2) = 0 Then you would have seen that the roots are -5 and 2, rather than what ...

**Math**

no square matrix can have 8 elements!

**math**

not knowing the prices is a bit of a hindrance. However, if the prices were x and y, and there were s seniors, then sx + y(205-s) = 1930 So, plug in your values for the ticket prices, and solve for s.

**Math**

70 * (1-.25) * 1.06 = 55.65

**Math**

google Heron's formula

**math**

see your earlier post

**math**

solve the equations in pairs: 4x+y=1 2x-y=5 intersect at (1,-3) Now do the same for the other pairs: 4x+y=1 3y+3x=12 2x-y=5 3y+3x=12

**inequalities mathh 7a**

the monthly fee m is figured by subtracting the entry fee ($100) and dividing the rest by the number of months: m = (700-100)/12 = 600/12 = 50

**inequalities mathh 7a**

Your keyboard has all the symbols you need to type math problems.

**inequalities mathh 7a**

ever hear of real math symbols? r/2 - 6 = 14 r/2 = 20 r = 40

**math**

the two equations are y = 12x y = 120+2x

**Math**

if you just want to simplify it, add like terms: (14-12)x^2 + (3+11)x + (4-3) 2x^2 + 14x + 1

**Algebra**

2x^2-3x+1 = (2x-1)(x-1) x^2-6x+1 is a little harder, as it has no rational roots. So, use the quadratic formula to get x = 3±2?2

**Math**

There are 8 socks, so 3/8 * 2/8

**Math**

Assuming any number can follow any other, there are 50^3 combinations. If there are some restrictions, then that number will be reduced.

**Math**

write it as 5*3^n and you have 5*3^0 = 5*1 = 5 5*3^1 = 5*3 = 15 5*3^2 = 5*9 = 45 5*3^3 = 5*27 = 135 starts with 5, not 0

**geometry**

If she walked on the track, it's an arc of a circle. she walked 2/3 of the circumference. As you recall, the circumference of a circle of radius r is C = 2?r. An arc of a circle of radius r that covers an angle ? is s = r? So, the friend walked through an angle ? such that...

**Math**

If there are x students, then 3/8 x + 3/5 x + 20 = x now just solve for x

**Math**

just crank it out... sin(?-30°)+cos(?+30°) = sin? cos30 - cos? sin30 + cos? cos30 - sin? sin30 = ?3/2 sin? - 1/2 cos? + ?3/2 cos? - 1/2 sin? = (?3/2 - 1/2)sin? + (?3/2 - 1/2) cos? = (?3-1)/2 (sin?+cos?) = (?3/-1)/?2 (sin?/?2 + cos?/?2) = (?3-1)/?2 sin(?+45)

**Math**

if there were a adults, then the rest (8-a) were students. So, adding up the prices, 10a + 8(8-a) = 78

**Algebra**

correct

**Algebra**

The terms are powers of 3, so it's a geometric sequence with common ratio 3. So, S10 = 1(3^10-1)/(3-1) = 29524

**Algebra**

bring it on!