# Posts by Steve

Total # Posts: 52,260

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!

Algebra
(6-x)/(x^2+2x-3) -------------------- (x^2-4x-12)/(x^2+4x+3) (6-x)/(x+3)(x-1) ----------------------------- (x-6)(x+2) / (x+3)(x+1) (6-x)/((x+3)(x-1)) * ((x+3)(x+1))/((x-6)(x+2)) (6-x)(x+3)(x+1) ------------------------- (x-6)(x+2)(x+3)(x-1) -(x+1)/((x+2)(x-1)) -(x+1)/(x^2+x-2...

Calculus
Are you looking for a piecewise function? If so, a simple step function will do the job. f(x) = 0.1 for 0 <= x < 1 0.2 for 1 <= x < 2 0.4 for 2 <= x <= 2.5 You can do similar things with sloping lines, but you will get trapezoids or triangles to work with. If...

math
nah - that's what I got.

math
the distance traveled is the same: 126 km. So, since distance = speed * time, 6(b-c) = 126 4.5(b+c) = 126

Algebra Help ASAP
all correct. good work

One more question Calculus
the acceleration graph is apparently a(t) = 10-t so, that gives us v(t) = 10t - t^2/2 + C v(0)=0, so C=0 so, now we have s(t) = 5t^2 - t^3/6 + C s(0) = 10, so C = 10 s(t) = 10 + 5t^2 - t^3/6 s(30) = 0 So, the final position is 10 ft behind the starting line. However, the total...

You have found the net rate of change of the water (since E and F are measured in pints/minute) at t=5, not the amount of water. dA/dt = F(t)-E(t) = (t+7)/(2+t) - (ln(t+4))/(t+2) Unfortunately, ln(t+4)/(t+2) does not integrate using elementary functions. Also, without knowing ...

Calculus really quick check
I agree.

Math
If the bus's speed is x, then since time = distance/speed, 180/x = 240/(x+15)

math

?[1,x] 2t+2 dt = t^2+2t [1,x] = (x^2+2x)-(1^2+2*1) = x^2+2x-3 ?[0,x] ?(4-t^2) dt = 1/2 ?(4-t^2) + 2 arcsin(t/2) [0,x] = 1/2 ?(4-x^2) + 2arcsin(x/2) - (1/2 ?(4-0) + 2 arcsin(0)) = 1/2 ?(4-x^2) + 2arcsin(x/2) - 1 The domain is clearly [-2,2] The range is [-?-1,?-1] http://www....

math
6*5*5 = 150 ft^3 Now just convert ft^3 to liters.

Math
well, you have the formula. So, v = s^3 = (3/4 in)^3 = 27/64 in^3

Math
If x passed both, then 45+52-x = 64

geometry
42

algerbra
all correct You can write >= for "greater than or equal" same for <= as intervals, the domain and range are x?[0,?) and y?[2,?)

Come to think of it, I changed my mind. g'(0.2) = f'(0.4)*2 = -8

#1 not D, since f' is always increasing, f" cannot be zero anywhere. So, no inflection points. I like C, since f'(0) = 0. f has a minimum, since f" > 0 and thus f is concave up. g(x) = f(2x), so g'(x) = f'(2x)*2 g'(0.2) = f'(0.2)*2 = 2*2 = ...

caculus
the length z of cord is z^2 = x^2 + 60^2 z dz/dt = x dx/dt when z=100, x=80, so 100 dz/dt = 80 * 5 dz/dt = 4

Math
a:p = 2:1 = 10:5

Math
2 negatives negative to odd power is negative

Math
log16 - 2logx

Math
what is the mean proportional for any two numbers?

math
consider a hexagon. The triangle's sides join alternate vertices of the hexagon.

maths
you want to divide the length into 9 equal parts. Place z 4/9 of the way from x to y.

#1 ok #2 4^x grows faster than any polynomial #3 I think more likely (-4,0), as in y = 2sin(pi/4 x) http://www.wolframalpha.com/input/?i=2sin(pi%2F4+x)

English
A little-known fact is that "shall" is used for first person: I shall arise and go now. "will" is used for 2nd and 3rd person. They will have a great time. These are reversed in the imperative mood. That is why the Ten Commandments read Thou shalt not steal...

Math
For the code, something like count=0 for i=1..2000   with student[i] do {     read   name,sex,score     pct = score*5/2     sub45 = false     if pct < 45 then   &...

math
surely you meant If the diagonal of a square is 14 m, what is the area? well, if the diagonal is d, the area is d^2/2 because if the square's side is s, the area is s^2. The diagonal is s?2, so d^2 = 2s^2

English language
if the predicate contains two nouns, usually one will be a direct object, and other the indirect object. The indirect one answers the question: to whom? or for whom? so, what are your choices? Not all of the sentences contain both objects.

English language
usually, the first noun in the sentence is the subject. After that, the rest is predicate. What are your choices?

maths
YZ = 2(6 sin50°)

maths
how do the two figures relate? One diagonal of a rhombus does not tell you anything about its sides or angles.

maths
as with all triangles, the smallest angle is opposite the smallest side. So, it is opposite the side of 5cm, and tan? = 5/8

math
just plug it into the formula: 15000(1+.095/4)^(4*5)

Math. HELP!
#1. remember the slope-intercept form? y = mx+b #2. The slope is (1+3)/(3-1) = 2 So, the point-slope form is y-1 = 2(x-3) Now rearrange that into slope-intercept form. #3 -4y = 8x so, y = -2x for the equation y = kx, k is the constant of variation #4. y = kx, so y/x = k, a ...

math
S = a/(1-r) a = 2r, so 2r/(1-r) = 4 Now just solve for r, and you can then get A3 = ar^2

math
-48/6 = r^3 Now you can figure a, and then S11 = a(r^11-1)/(r-1)

math
a+39d = -54 S15 = 15/2 (2a+14d) S30 = 30/2 (2a+29d) So, 15/2 (2a+14d) + 30/2 (2a+29d) = 0 or, a+12d = 0 Now you have two equations, and you can find a and d, and then the sum S40.

math
no way for me to see. However, check your graph against this one: http://www.wolframalpha.com/input/?i=y%5E3+%3D+x-2

mathematics
but there are many online articles that show how to do it.

Mathematics Algebra
But (x^2 + 2x +4)/(x^2 - 2x - 4) does not always fit into the interval [1/3,3]. If x is very close to 1±?5 then the value is arbitrarily large f(3.2) = -129 plus, you have a typo. I think you mean [9.(3)^2x + 6.(3)^x + 4]/[ 9.(3)^2x - 6.(3)^x +4] using u = 3.3^x That ...

maths
huh?

Mathematics
"real"ize the denominator by multiplying top and bottom by 1-i sinx. Now you have [tan 2x - i(sinx+cosx)][1 - i sinx]/[(1-i sinx)(1+i sinx)] [tan2x - (sinx+cosx)(sinx) + i(junk)]/(1+sin^2 x) to get zero real part, we need tan2x = sin^2x + sinx cosx any multiple of ? ...

Math
For the code, something like count=0 for i=1..2000   with student[i] do {     read   name,sex,score     pct = score*5/2     sub45 = false     if pct < 45 then   &...

Math
If there are x cars and y yellow cars, clearly the new car is yellow, since 1/9 > 1/10 y = x/10 y+1 = (x+1)/9 There are now 81 cars, with 9 yellow.

trigonometry
draw the diagram, and it is clear that the distance x is x/100 = tan 50°11'10"

Math
c+d = 500 .75c + .50d = 275

math
so, you used 304 ft of fence.

Math, factoring
Divide by (x^2-x-6) and you get quotient: x^2+(a+1)x+(2a+7) remainder: (8a+24)x + b+6(2a+7) For the remainder to be zero, we need a = -3 b = -6 So, x^4-3x^3-3x^2+11x-6 = (x+2)(x-3)(x^2-2x+1) The other roots are 1,1