Contact us
Choose a category below so we can get back to you as quickly as possible.
x^2-9y^2+4z^2+4xz =x^2+4z^2+4xz-9y^2 =(x+2z)^2-9y^2 因為x+2z=-3y 所以原式=(-3y)^2-9y^2 =9y^2-9y^2 =0
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.