$xy=?$

Algebra Level 1

Given: $(x+y)^2=196 \text { and } (x-y)^2= 144$

Then, $xy=?$

1 solution

Ram Mohith
Jul 30, 2018

$(x + y)^2 - (x - y)^2 = 4xy$

$\implies 4xy = 196 - 144$

$\implies 4xy = 52$

$\implies xy = \dfrac{52}{4} = 13$

In fact x=13, y=1 is a solution to the problem. There is at least one more.

My initial solution was the same as yours was.

Steven Perkins - 2 years, 10 months ago