Question

(3х+1)(3х+1) - (3х-2)(2+3х) = 17

Answer 1

9х²+3х+3х+1-(6х+9х²-4-6х)=17
9х²+6х+1-9х²+4=17
6х+5=17
6х=17-5
6х=12
х=2

Answer 2

9х^2+3x+3x+1-6x-9x^2+4+6x=17 (Выделенное сокращается) 
6х+5=17
6х = 17-5
6х = 12
х = 2