Question

Thay ? bằng biểu thức thích hợp.

a)      \(\left( {x - 3y} \right)\left( {x + 3y} \right) = {x^2} - ?\);

b)      \(\left( {2x - y} \right)\left( {2x + y} \right) = 4? - {y^2}\);

c)      \({x^2} + 8xy + ? = {\left( {? + 4y} \right)^2}\);

d)      \(? - 12xy + 9{y^2} = {\left( {2x - ?} \right)^2}\). 

Answer 1

a)      \(\left( {x - 3y} \right)\left( {x + 3y} \right) = {x^2} - 9{y^2}\);

b)      \(\left( {2x - y} \right)\left( {2x + y} \right) = 4{x^2} - {y^2}\);

c)      \({x^2} + 8xy + 16{y^2} = {\left( {x + 4y} \right)^2}\);

d)      \(4{x^2} - 12xy + 9{y^2} = {\left( {2x - 3y} \right)^2}\).