Question

Đưa về dạng tích

7x(x-5)+4x-20

(3x-1)²-16

Answer 1

\(7x\left(x-5\right)+4x-20\)

\(=7x\left(x-5\right)+4\left(x-5\right)\)

\(=\left(x-5\right)\left(7x+4\right)\)

\(\left(3x-1\right)^2-16\)

\(=\left(3x-1-16\right)\left(3x-1+16\right)\)

\(=\left(3x-17\right)\left(3x+15\right)\)

Answer 2

\(7x\left(x-5\right)+4x-20\)

\(=7x\left(x-5\right)+4\left(x-5\right)\)

\(=\left(x-5\right)\left(7x+4\right)\)

\(\left(3x-1\right)^2-16\)

\(=\left(3x-1\right)^2-4^2\)

\(=\left(3x-1-4\right)\left(3x-1+4\right)\)

\(=\left(3x-5\right)\left(3x+3\right)\)

\(=3\left(x+1\right)\left(3x-5\right)\)

Answer 3

\(\left(3x-1\right)^2-16\)

\(\left(3x-1\right)^2-4^2\)

\(\left(3x-1+4\right).\left(3x-1-4\right)\)

\(\left(3x+3\right).\left(3x-5\right)\)

\(\Rightarrow3.\left(x+1\right).\left(3x-5\right)\)

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