# 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 ...

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...

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 = ...

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

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

(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

math

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!

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