Question

Đề bài : tính

(x-5)(2-x) -\left(x-1\right)^2
\((x−1)^2\)

 

 

Answer 1

\(=2x-x^2-10+5x=7x-x^2=10\)

Answer 2

\(=x\left(2-x\right)-5\left(2-x\right)\)

\(=2x-x^2-10+5x\)

\(=-x^2+2x+5x-10=-x^2+7x-10\)

Answer 3

\(\left(x-5\right).\left(2-x\right)-\left(x-1\right)^2=x^2+2x-10+5x-x^2-2x+1=5x-9\)