a,2x²y - 7x⁷

^{c,\(\dfrac{x}{x-2}\)}

a, 3 (x + 2 ) - 2 =10                                           

3x + 6 - 2 = 11                 

3x+4 =10

3x      = 10-4

3x       = 6

x         = 6 : 3

x         = 2

Vậy x = 2
b,x² - 5x + 6 = 0

x² - 2x -3x + 6 = 0

(x² - 2x) - (3x - 6 ) = 0

x(x - 2 ) - 3( x  - 2) = 0

(x - 2 ) (x-3)  = 0

Th1 : x- 2 = 0

         x = 0+ 2

         x =2

TH2 

        x-3 =0

        x= 0+ 3

       x= 3 

Vậy x thuộc {2 ; 3 }