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1) 2x(x + 1)2 - (x - 1)3 - (x - 2)(x2 + 2x + 4)
= 2x3 + 4x2 + 2x - x3 + 3x2 - 3x + 1 - x2 + 8
= 7x2 - x + 9
2) (3x + 5)2 + (3x - 5)2 - (3x + 2)(3x - 2)
= 9x2 + 30x + 25 + 9x2 - 30x + 25 - 9x2 + 4
= 9x2 + 54
A=\(\left(x^2+3x+1\right)\left(\left(3x-1\right)^2+2\left(1-3x\right)\right)\)
A=\(\left(x^2+3x+1\right)\left(9x^2-6x+1+2-6x\right)\)
A=\(\left(x^2+3x+1\right)\left(9x^2+3\right)\)
A = (2x + 3)2 + (3x - 2)2 + 2(2x + 3)(3x - 2) = (2x + 3 + 3x - 2)2 = (5x + 1)2
a) (3x + 1)^2 - 2(3x + 1)(3x - 5) + (3x - 5)^2
= 9x^2 + 6x + 1 - 18x^2 + 24x + 10 + 9x^2 - 30x + 25
= 36
b) (3x^2 - y)^2
= 9x^4 - 6x^2y + y^2
c) (3x + 5)^2 + (3x - 5)^2 - (3x + 2)(3x - 2)
= 9x^2 + 30x + 25 + 9x^2 - 30x + 25 - 9x^2 + 4
= 9x^2 + 54
d) 2x(2x - 1)^2 - 3x(x + 3)(x - 3) - 4x(x + 1)^2
= 8x^3 - 8x^2 + 2x - 3x^2 + 27x - 4x^3 - 8x^2 - 4x
= x^3 - 16x^2 + 25x
e) (x - 2)(x^2 + 2x + 4) - (x + 1)^2 + 3(x - 1)(x + 1)
= x^3 - 8 - x^2 - 2x - 1 + 3x^2 - 2
= x^3 + 2x^2 - 2x - 12
f) (x^4 - 5x^2 + 25)(x^2 + 5) - (2 + x^2)^2 + 3(1 + x^2)^2
= x^6 + 125 - 4 - 4x^2 - x^2 + 3 + 6x^2 + 3x^4
= x^6 + 2x^4 + 2x^2 + 124
đay là hằng đẳng thức nhé
((3x+1) - (3x-5))2 = (3x+1-3x+5)2 = 62 = 36
\(\left(3x+2\right)^2+\left(3x-2\right)^2-2\left(3x+2\right)\left(3x-2\right)+x\\=\left[\left(3x+2\right)^2-2\left(3x+2\right)\left(3x-2\right)+\left(3x-2\right)^2\right]+x \\=\left(3x+2-3x+2\right)^2+x\\ \\=4^2+x\\ \\=x+16\)