Question

tìm x

a) (x-5)(x+5) = (x-2)

b) (3-2x)² - (x-5)(4x+3)= 2(x+5)

c) (7-x)(2x-5)-(7-x)2x= 3(-5+x)

Answer 1

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

    \(x^2-25-x+2=0\)

   \(x^2-23-x=0\)

    \(x.\left(x-1\right)=23\)

        Bài này vô lý quá

b)\(\left(3-2x\right)^2-\left(x-5\right)\left(4x+3\right)=2\left(x+5\right)\)

    \(9-12x+4x^2-4x^2-3x+20x+15=2x+10\)

   \(5x+24=2x+10\)

   \(5x+24-2x-10=0\)

  \(3x-14=0\)

   \(3x=14\)

  \(x=\frac{14}{3}\)

Vậy \(x=\frac{14}{3}\)

      

 

 

Answer 2

c)\(\left(7-x\right)\left(2x-5\right)-\left(7-x\right)2x=3\left(-5+x\right)\)

   \(\left(7-x\right)\left[\left(2x-5\right)-2x\right]=\left(-15\right)+3x\)

   \(5x-35=\left(-15\right)+3x\)

   \(5x-35+15+3x=0\)

   \(8x-20=0\)

  \(8x=20\)

  \(x=\frac{5}{2}\)

Vậy \(x=\frac{5}{2}\)