How do you factor #45x^2-20m^2#?
1 Answer
Apr 15, 2018
Explanation:
#"take out a "color(blue)"common factor "5#
#=5(9x^2-4m^2)#
#9x^2-4m^2" is a "color(blue)"difference of squares"#
#"which in general factors as"#
#•color(white)(x)a^2-b^2=(a-b)(a+b)#
#"note that "(3x)^2=9x^2" and "(2m)^2=4m^2#
#"thus "a=3x" and "b=2m#
#rArr9x^2-4m^2=(3x-2m)(3x+2m)#
#rArr45x^2-20m^2=5(3x-2m)(3x+2m)#
