How do you evaluate #\frac { x ^ { 2} - y ^ { 2} } { y - x }#?
1 Answer
Mar 27, 2018
Explanation:
#"factorise the numerator"#
#x^2-y^2larr" is a "color(blue)"difference of squares"#
#•color(white)(x)a^2-b^2=(a-b)(a+b)#
#rArrx^2-y^2=(x-y)(x+y)#
#"on the denominator take out a "color(blue)"common factor"#
#"of "-1#
#rArry-x=-1(x-y)#
#color(blue)"cancel ""common factors on numerator/denominator"#
#rArr(x^2-y^2)/(y-x)#
#=(cancel((x-y))(x+y))/-cancel((x-y))=-(x+y)#
