How do you solve $y^2 - 9 = 0$ by factoring?

Question

2896 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-08-16T17:07:01

The solutions are

$color(blue)(y=3$
$color(blue)(y=-3$

$y^2−9=0$

The expression is of the form $y^2−9=y^2-3^2$

And as per property:
$color(blue)(a^2-b^2=(a+b)(a-b)$

Applying the same property and factorising we get:

$y^2−3^2 = color(blue)((y-3)(y+3)$

Now the factors can be equated to zero to obtain solutions.

$y-3=0 , color(blue)(y=3$
$y+3=0 , color(blue)(y=-3$

How do you solve y^2 - 9 = 0y^2 - 9 = 0 by factoring?