Question

[hoangtuvi]

viết mỗi biểu thức sau dưới dạng hiệu hai bình phương:

a) (x+y+4)(x+y-4)

b) (y+2z-3)(y-2z-3)

c) (x-y-6)(x+y-6)

d) (x+2y+3z)(2y+3z-x)

Answer 1

[Lê Ng Hải Anh]

a, \(\left(x+y+4\right)\left(x+y-4\right)=\left(x+y\right)^2-4^2\)

b, \(\left(y+2z-3\right)\left(y-2z-3\right)=\left(y-3+2z\right)\left(y-3-2z\right)=\left(y-3\right)^2-\left(2z\right)^2\)

c, \(\left(x-y-6\right)\left(x+y-6\right)=\left(x-6-y\right)\left(x-6+y\right)=\left(x-6\right)^2-y^2\)

d, \(\left(x+2y+3z\right)\left(2y+3z-x\right)=\left(2y+3z+x\right)\left(2y+3z-x\right)=\left(2y+3z\right)^2-x^2\)