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

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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.

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