How do you solve x^2-75=0x275=0?

1 Answer
Aug 17, 2016

x=+-5sqrt(3)x=±53

Explanation:

Treat x^2-75x275 as the difference of squares

We know that a^2-b^2=(a-b)(a+b)a2b2=(ab)(a+b)

So replacing aa with xx
and bb with 5sqrt(3)53 (so that b^2=75b2=75)
we have
color(white)("XXX")x^2-75=0XXXx275=0
is equivalent to
color(white)("XXX")(x-5sqrt(3))(x+5sqrt(3))=0XXX(x53)(x+53)=0

which implies
either (x-5sqrt(3))=0 color(white)("XX")orcolor(white)("XX") (x+5sqrt(3))=0(x53)=0XXorXX(x+53)=0
color(white)("XX")rarr x=5sqrt(3)color(white)("XXXXXXXX")rarrx=-5sqrt(3)XXx=53XXXXXXXXx=53