If y varies directly with x, and y = 64 when x = 4, find the constant of variation k.?

Answer 1

If it varies directly it means:
y = kx

Here k is the constant of variation.

Simply plug in your known values of x and y and solve for k:

64 = k(4)
64 = 4k

Divide both sides by 4:
64/4 = k
16 = k
k = 16

The constant of variation (k) is 16.

P.S. If it varied *indirectly* you would use k = xy or equivalently y = k/x

Answer 2

Y = kx
k = Y/x
= 64/4
=16

Answer 3

y=x that bit was easy

y=x+c

64=4+c so C = 60

now rewrite it wth K replacing C


See how messed up it all becomes when someone uses different conventions and silly phrases

Standard linear equation is Y= MX +C where M= the GRADIENT or SLOPE and C is the constant (the y intercept when x=0)

Answer 4

Y = K * X

64 = K * 4


K = 16