Tính:
a) (2x + 3)3 = (2x)3 + 3.(2x)2.3 + 3.2x.32 + 33 = 8x3 + 36x2 + 54x + 27
b) (2x - 3)(4x2 + 6x + 9) = (2x - 3)[(2x)2 + 2x.3 + 32] = (2x)3 - 33 = 8x3 - 27
c) (3x + 4y)(9x2 - 12xy + 16y2) = (3x + 4y)[(3x)2 - 3x.4y + (4y)2] = (3x)3 + (4y)3 = 27x3 + 64y3.
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a. (2x+3)3 = (2x)3+3.(2x)2.3+3.2x.32+33=8x +36x2+54x2+9=8x+90x2+9
b. (2x-3) (4x2+6x+9) = 2x.4x2+2x.6x+2x.9-3.4x2-3.6x-3.9 = 8x3+12x2+18x-12x2-18x-27 = 8x3-27
c. (3x+4y) (9x2-12xy+16y2) = 3x.9x2-3x.12xy+3x.16y2+4y.9x2-4y.12xy+4y.16y2= 27x3-36x2y+48xy2+36x2y-48xy2+64y3
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