Question

якщо (x-у)² = 25, x²-y²= 20, тo (x + y)²=

Answer 1

Ответ:

$(x+y)^2=16$

Объяснение:

$(x-y)^2=25\ \ \ |\sqrt{} \\\\|x-y|=5\\\\x-y=-5\ \ \ \ \ \ \ \ \ x-y=5\\\\\\\\x^2-y^2=20\\\\(x-y)(x+y)=20\\\\-5(x+y)=20\ \ \ |:(-5)\ \ \ \ \ \ \ \ \ \ 5(x+y)=20\ \ \ |:5\\\\x+y=-4\ \ \ |()^2\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x+y=4\ \ \ |()^2\\\\(x+y)^2=16\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (x+y)^2=16$