a) \(4x^2+y^2-25+4xy\\ =\left(4x^2+4xy+y^2\right)-25\\ =\left(2x+y\right)^2-5^2\\ =\left(2x+y-5\right)\left(2x+y+5\right)\)
b) \(\left(x-3\right)^2-\left(x+2\right)^2\\ =\left(x-3-x-2\right)\left(x-3+x+2\right)\\ =-5\left(2x-1\right)\)
Đúng 3
Bình luận (2)
a. 4x2 + y2 - 25 + 4xy
= (2x)2 + 4xy - 52 - 52
= (2x + 5)2 - 52
= (2x + 5 - 5)(2x + 5 + 5)
= 2x(2x + 10)
Đúng 1
Bình luận (2)
