Đáp án:
bài 2a)
(2x+1)²
=4x²+4x+1
b)(2y-1)²
=4y²-4y+1
c)(4x-3)(4x+3)
=16x²-9
d)x³+216
=(x+6)(x²-6a+36)
f)216y³-1
=(6y-1)(36y²+6y+1)
bài 3
a)(x-3)(x²+3x+9)+x(x+2)(2-x)=1
⇔x³-27-x(x+2)(x-2)=1
⇔x³-27-x(x²-4)=1
⇔x³-27-x³+4x=1
⇔4x-27=1
⇔4x=28
⇔x=7
b)(x+1)³-(x-1)³-6(x-1)²=-10
⇔x³+3x²+3x+1-(x³-3x²+3x-1)-6(x²-2x+1)=-10
⇔x³+3x²+3x+1-x³+3x²-3x+1-6x²+12x-6=-10
⇔-4+12x=-10
⇔12x=-6
⇔x=$\frac{1}{2}$
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