Question

Phân tích các đa thức thành nhân tử.

a) x²-4x-5 b) x⁴+4x²-5

c) x²+x-6 d) x²+5x+6

e) x²-x-6

Có ai đang on ko giúp mik với nhà.Giải cụ thể giùm mik nữa nhé!!!!!!!!!!

Answer 1

a) \(x^2-4x-5\Leftrightarrow x^2+x-5x-5\Leftrightarrow x\left(x+1\right)-5\left(x+1\right)\)

\(\Leftrightarrow\left(x-5\right)\left(x+1\right)\)

b) \(x^4+4x^2-5\Leftrightarrow x^4-x^2+5x^2-5\Leftrightarrow x^2\left(x^2-1\right)+5\left(x^2-1\right)\)

\(\Leftrightarrow\left(x^2+5\right)\left(x^2-1\right)\Leftrightarrow\left(x^2+5\right)\left(x+1\right)\left(x-1\right)\)

c) \(x^2+x-6\Leftrightarrow x^2-2x+3x-6\Leftrightarrow x\left(x-2\right)+3\left(x-2\right)\)

\(\Leftrightarrow\left(x+3\right)\left(x-2\right)\)

d) \(x^2+5x+6\Leftrightarrow x^2+2x+3x+6\Leftrightarrow x\left(x+2\right)+3\left(x+2\right)\)

\(\Leftrightarrow\left(x+3\right)\left(x+2\right)\)

e) \(x^2-x-6\Leftrightarrow x^2+2x-3x-6\Leftrightarrow x\left(x+2\right)-3\left(x+2\right)\)

\(\Leftrightarrow\left(x-3\right)\left(x+2\right)\)