# Math

DIRECT VARIATION

1. a is directly proportional to b.If a=15,then b=9
2. m varies directly as n.If n=2/3,then m=1/4
3. T varies as the square root of L. If L=81,then T=10
4.r varies directly as the square of t. If t=16,then r=6.
5. y varies as the cube foot of x. If x=27,then y=2.
6. y is directly proportional to x. If y=15 when x=4,find y when x=5.
7. m varies directly as n. If m= -6 when n=2,find m when n=-3
8. The square of x varies directly as the cube of y. When x=2,y=4,find y when x=8

1. What do you want for #1 - 5 ?
Are you finding the constant of variation or what?

I will do one of them, #4

r varies directly as the square of t. ---> r = kt^2
when t=16, r=6
6 = k(16)^2
6 = 256k
k = 6/256 = 3/128

so r = (3/128)t^2

#8.
The square of x varies directly as the cube of y. ---> x^2 = ky^3
when x=2, y=4
4 = k(64)
k = 4/64 = 1/16
so x^2 = (1/16)y^3
when x = 8
64 = (1/16)y^3
y^3 = 1024
y = 1024^(1/3) = 8cuberoot(2)

Do the others the same way.
let me know what you got for the rest.

posted by Reiny

## Similar Questions

1. ### Algebra worksheet

Hello. My algebra teacher gave me this worksheet last week and everyone had to bring it yesterday and I haven't done it yet. Can someone please help me. He said Friday is the last day or he's going to take away some points. I've
2. ### Variation

I have few questions that I need checked please and could you help me with the last question? Write an equation that expreses the relationship. Use k as the constant of varaiation. 1. s varies directly as h -I got: s=kh 2.a varies
3. ### algebra1

M varies directly with n; m=144 when n=8. What is the constant of variation k? I don't know what this mean. Could you help me out in solving this/ A statement such as "M varies directly with n" can be changed to the equation M=kn,
4. ### math

t varies directly as the square root of l. If l=81, then t=10 what is the constant proportion? 1. a is directly proportional to b. If a = 15, then b = 9 2. M varies directly as n. If n = 2/3, then m = 1/4 3. T varies as the square
5. ### math

This is about direct variation. The area a painter can paint varies directly with the amount of time he works. One morninig, he painted 204 ft² between 8 a.m. and 12:15 PM. Write a direct variation equation to describe the area y
6. ### Algebra

This is about direct variation. The area a painter can paint varies directly with the amount of time he works. One morninig, he painted 204 ft² between 8 a.m. and 12:15 PM. Write a direct variation equation to describe the area y
7. ### Math

This is regarding direct variation. y varies directly as the square of R. If y = 128 when R = 8, find y when R = 5. Another one I cannot figure out: If x varies directly as y, and x = 32 when y = 8, find x when y = 10 Help!
8. ### algebra

I have no clue what to do here can you tell me how to figure this? If y varies directly with x, and y = 500 when x = 200, find the constant of variation k. Whenever you have a statement such as "....y varies directly with x..."
9. ### Pre-Calc

1.) Suppose that y varies directly as x. If y is 5 when x is 30, the constant of variation is 150. True Or False 2.) If w varies directly as z and w = 9 when z = -6, find w when z = 3. 3.) If y varies directly as x and y = 2 when
10. ### Algebra 2 Honors

Hey, we recently started a topic in class that I don't understand well, I just want to post 6 of the problems and ask if they're right or not (some of them I have no idea how to do). 1. If a varies directly as b and b = 18 when a

More Similar Questions