How do you solve #x^2 − 25 = 0#?

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Answer 1 · 2016-05-06T12:02:53

#x=+-5#

There are two ways of doing this.

#color(blue)("Method 1")#

Add 25 to both sides

#x^2-25+25=25#

#"but "-25+25=0#

#x^2=25#

#color(blue)(x=sqrt(25)=+-5)#
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Method 2")#

Using #a^2-b^2=(a+b)(a-b)#

Write#" " x^2-25=0" as "x^2-5^2 = 0 ->(x-5)(x+5)=0#

#color(blue)(x=+-5)#