Question

Suppose y varies directly with x and y = 72 when x = 6. What direct variation equation relates x and y? What is the value of y when x = 10?

Answer 1

y varies directly with x
mean for some constant k with have the equation y=kx

Answer 2

you are given a point on the line y=kx
that point being (6,72) <---plug into find the constant k

Answer 3

thank you

Answer 4

let me know when you have found the constant k

Answer 5

no sorry

Answer 6

so you aren't able to solve the equation 72=6k for k?

Answer 7

if you aren't able to, can you at least think of number when multiplied to 6 gives you 72?

Answer 8

A. y=1/9x;10/9
B. y=x+9;19
C. y=9x;90
D. y=x−9;1

Answer 9

none of those are the answer

Answer 10

but anyways back to the question

Answer 11

can you solve 72=6k for k?

Answer 12

i dont really know

Answer 13

you must have solved linear equations like 6k=72 before?
notice the k is being multiplied by 6
divide both sides by 6 to isolate k

Answer 14

k=12

Answer 15

great
so this is what we have done so far

we were given
that y varies directly with x which means the equation has form y=kx
where k is a constant

we we given that y=72 when x=6 which means the point (6,72) is on the line y=kx
we plug this point in giving us
72=k*6
or
72=6k
and then divided both sides by 6
72/6=k
12=k

so we now know the constant k for any point (x,y) for this line which is 12
so the equation is y=12x

now we are asked to find y when x is 10
so replace x with 10 now to find the corresponding y value

Answer 16

okay

Answer 17

did you want to tell me what you got for y when you replaced x with 10?