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Jinglander
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x+y=a implies (x + y)^2 = a^2 or x^2 + y^2 + 2xy = a^2...Equation (1)Jinglander wrote:x+y=a and
x-y=b
what is 2xy
answer is
(a^2-b^2)/2
How do you solve this by alg
x - y=b implies (x - y)^2 = b^2 or x^2 + y^2 - 2xy = b^2...Equation (2)
Subtract Equations (1) and (2) above, 4xy = a^2 - b^2
or 2(2xy) = a^2 - b^2
or 2xy = (a^2-b^2)/2
