chào Yasou!
a)(1 + x)2 + (1 – x)2
<=> 1+2x+x^2+1-2x+x^2
<=> 2+2x^2
<=>2(1+x^2)
b. (x - 3)2 + 3(x + 1)2
<=> x^2-6x+9+3(x^2+2x+1)
<=> x^2+9+3x^2+1
<=> 4x^2 +10
<=> 2(2x^2+5)
c. (x + 5) (x – 2) – (x + 2)2
<=> x^2-2x+5x-10-x^2-4x-4
<=> -x-14
d. (4x – 1) (4x + 1) – 4(1 – 2x)2
<=> 16x^2+4x-4x-1-4(1-4x+4x^2)
<=> 16x^2-1-4+16x-16x^2
<=> -5+16x
chúc bạn học tốt!