How do you factor #x^2-9#?

2 Answers
Jim G.
Mar 20, 2018

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

Explanation:

#x^2-9" is a "color(blue)"difference of squares"#

#"and in general factorises as"#

#•color(white)(x)a^2-b^2=(a-b)(a+b)#

#"here "a=x" and "b=3#

#rArrx^2-9=(x-3)(x+3)#

smendyka
Mar 20, 2018

See a solution process below:

Explanation:

This is a special case of the quadratic:

#color(red)(x)^2 - color(blue)(y)^2 = (color(red)(x) + color(blue)(y))(color(red)(x) - color(blue)(y))#

#(x^2 - 9 =>#

#color(red)(x)^2 - color(blue)(3)^2 =>#

#(color(red)(x) + color(blue)(3))(color(red)(x) - color(blue)(3))#

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