Question

(7x+1)(x-3)+20(x-1)(x+1)=3(3x-2)²+13

Answer 1

7х^2-21х+х-3+20(х^2-1)=3(9х^2-12х+4)+13
7х^2-21х+х-3+20х^2-20=27х^2-36х+12+13
27х^2-20х-23=27х^2-36х+25
-20х-23=-36х+25
-20х+36х=25+23
16х=48
х=3