How do you solve #x^2-9=0#?

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Answer 1 · 2018-04-23T01:01:24

#3#

Start out by adding #9# to both sides to isolate the variable:

#x^2 - 9 = 0#

#x^2 cancel(-9 color(red)( +9)) = 0 color(red) (+ 9)#

#x^2 = 9#

Now find the square root of both sides:

#sqrt(x^2) = sqrt9#

#x = 3#

Answer 2 · 2018-04-23T01:02:17

#x=+-3#

This is an example of difference of squares: #a^2-b^2=(a-b)(a+b)#

Here, #a# is #sqrt(x^2)=x# and #b# is #sqrt9=3#

#(x-3)(x+3)#

#(x-3)(x+3)=0#

#x-3=0#

#x=3#

#x+3=0#

#x=-3#

Answer 3 · 2018-04-23T01:06:59

#x=-3,3#

Solve:

#x^2-9=0#

Add #9# to both sides.

#x^2=9#

Take the square root of both sides.

#sqrt(x^2)=+-sqrt9#

Simplify.

#x=+-3#