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

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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#