How do you solve #y=x^2, y=2x# using substitution?

Question

7808 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-01-30T18:49:10

Substitute 2x for y
Divide both sides by x.

Given:
#y = x^2" [1]"#
#y = 2x" [2]"#

Equation [2] allows the substitution of 2x for y into equation [1]:

#2x = x^2#

Subtract 2x from both sides.

#x^2 - 2x = 0#

Factor:

#x(x -2) = 0#

#x = 0 and x = 2#

Check:

#y = x^2" [1]"#
#y = 2x" [2]"#

#y = 0^2 and y = (2)^2#
#y = 2(0) and y = 2(2)#

#y = 0 and y = 4#
#y = 0 and y = 4#

This checks.