Question

Bài 1 : Rút gọn

a) (x+2)(x-2) - (x-2)(x+5 )

b) 2x(3x mũ 2 y + 4x mũ 2 y -3)

c) (3x+1) tất cả mũ 2 - (1 -2x) mũ 2

d) x mũ 2 -4-(x+2 ) mũ 2

e) (x-4)(x+4) -2x(x+3) + (x+3) mũ 2

f) (6x+1) mũ 2 -2(6x+1)(6x-1)+(6x-1) mũ 2

Answer 1

a) (x+2)(x-2) - (x-2)(x+5 )

= (x-2) (x+2 - x-5)

= -3 (x-2)

c) \(\left(3x+1\right)^2\) - \(\left(1-2x\right)^2\)

= (3x+1 - 1 +2x) (3x+1 +1-2x)

= 5x (x +2)

d) \(x^2\) - 4 - \(\left(x+2\right)^2\)

= (\(x^2\) - 4 ) - ( x+2) (x+2)

= (x-2) (x+2) - (x+2) (x+2)

= (x+2) (x-2 - x-2)

= -4 (x+2)

Answer 2

e: \(=x^2-16-2x^2-6x+x^2+6x+9=-7\)

b: \(=\left(6x+1-6x+1\right)^2=2^2=4\)