Question

 TÍNH  (x-1)(x+5)

Answer 1

\((x-1)(x+5)\\=x(x+5)-(x+5)\\=x^2+5x-x-5\\=x^2+4x-5\)

#\(Toru\)

Answer 2

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

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

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

\(=x^2-1^2+4x-4\)

\(=x^2+4x-5\)

Answer 3

(x-1)(x+5)

= x.x + x.5 - 1.x - 1.5

=x²   + 5x  - x    - 5

=x² + 4x - 5