Phân tích thành nhân tử:
a. x2 + 4x + 3
b. 2x2 + 3x – 5
c. 16x – 5x2 – 3
a. x2 + 4x + 3 = x2 + x + 3x + 3 = (x2 + x) + (3x + 3)
= x(x + 1) + 3(x +1) = (x + 1)(x + 3)
b. 2x2 + 3x – 5 = 2x2 – 2x + 5x – 5 = (2x2 – 2x) + (5x – 5)
= 2x(x – 1) + 5(x – 1) = (x – 1)(2x + 5)
c. 16x – 5x2 – 3 = 15x – 5x2 – 3 + x = (15x – 5x2) – (3 – x)
= 5x(3 – x) – (3 – x) = (3 – x)(5x – 1)
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