Question

Giúp mình nhé. 

1/ (x-3). (2x-5) -3x. (x+4)

2/ (1/2x+5). (2x- 1/5)

3/ (x²-3x+5). (2x-5)

Answer 1

1: \(\left(x-3\right)\left(2x-5\right)-3x\left(x+4\right)\)

\(=2x^2-5x-6x+15-3x^2-12x\)

\(=-x^2-23x+15\)

2: \(\left(\dfrac{1}{2}x+5\right)\left(2x-\dfrac{1}{5}\right)\)

\(=x^2-\dfrac{1}{10}x+10x-1\)

\(=x^2+\dfrac{99}{10}x-1\)