# Math

posted by .

Find the value of y for a given value of x, if y varies directly with x.

If y = –252 when x = 84, what is y when x = 74?

• Math -

y = kx
-252 = k(84)
k = -3

y(74) = -3(74) = -222

• Math -

Do the same thing with X 6, 18, 54, 162
Y 24, 72, 216, 640

2.52 = k(8.4)
K=0.03
Y(2.7)=0.03(2.7)=0.81

• Math -

f(x)=4x+7,find f(4)

## Similar Questions

1. ### algebra1

M varies directly with n; m=144 when n=8. What is the constant of variation k?
2. ### math,help

I definately do not understand this problem. If y varies directly with x, and y = 600 when x = 1000, find the constant of variation K. If y is directonally (proportional) to x, then for every value of x there is a value for y multiplied …
3. ### Math

S is directly proportional to M^3. It is given that S=36 for a certain value of M. Find the value of S when this value of M is (a) doubled (b) reduced by 40%
4. ### algebra

Find the value of y for a given value of x, if x varies directly with x. If y=39 when x=-117 what is y when x=-132 my answer y=k*x 39=k*-117 39/-117=k k=-0.3 y=k*x y=-0.3*-1.32 y=-3.96 can someone please check my work
5. ### math

when y varies directly at the square of X, the variation equation is written y= kx square, where K is constitution (a) given that y=50 when x=10,find the value of K. (b) calculate the value of y when X= 30
6. ### algebra

Find the value of y for a given value of x if y varies directly with x if y=2.52 when x=8.4,what is y when x=2.7 thanks
7. ### algebra

Show all steps Find the value of y fora given value of x if y varies directly with x If y =-252 when x=84, what is y when x=74?
8. ### Algebra

Find the value of y for a given value of x, if y varies directly with x. If y= -252 when x=84, what is y when x= 74?
9. ### math

S varies directly to the square of t. Given that S = 100, when t = 4, calculate the value of: a) k, the constant of proportionality b) S when t = 8 c) t when S = 1
10. ### Algebra2A

I am confused with this question: Find teh value of y for a given value of x, if y varies directly with x. If y = 6 when x = 2, what is y when x = 5?

More Similar Questions