Question

(3x+1)²+(x-2)(x+1)=-1

Answer 1

(3x+1)² + (x-2) (x+1) = -1 
9x² + 6x +1 + (x² +x -2x -2) = -1 
9x² + 6x +1 +x² +x -2x -2 +1 = 0 
10x² +5x = 0 
5x(2x +1) = 0 (x=0) 
2x +1 =0 
2x = -1 
x = -1/2 

S={-1/2, 0} 

Answer 2

(3x+1)² + (x-2)(x+1) = -1
9x² + 1 + x² + x - 2x - 2 + 1 = 0
10x² - x = 0
x=0

x (10-x) = 0
-x = - 10 . (-1)
x = 10