What should be taken away form 3x 2 - 4y 2 + 5xy + 20 to obtain -x 2 - y 2 + 6xy + 20?

Question

Philoid · Accepted Answer

Let k should be taken away from 3x² - 4y² + 5xy + 20

3x² - 4y² + 5xy + 20 - k = -x² - y² + 6xy + 20

k = 3x² - 4y² + 5xy + 20 - (-x² - y² + 6xy + 20)

k = 3x² - 4y² + 5xy + 20 + x² + y² - 6xy - 20

k = 4x² - 3y² - xy

What should be taken away form 3x2 - 4y2 + 5xy + 20 to obtain -x2 - y2 + 6xy + 20?