If y varies directly with x and y=21 when x=7, how do you find y when x=-1.66?

1 Answer
Mar 6, 2018

#y=-4.98#

Explanation:

This statement means #y propx#, which can also be written in the form #y=kx# when it is directly proportionate and #y=k/x#when inversely proportionate, where #k# is a value we need to work out.

Since the equation is in the form #y=kx# we know that...

#21=K xx 7#

#therefore# #k=21/7=3#.

So we can write this as the formula:

#y=3x#

Therefore using the value of #x=-1.66#

#y=3x -> y=3xx -1.66=-4.98#