3х(3х+7)-(3х+4)(3х-4)=9x^2+21x-(9x^2-16)=9x^2+21x-9x^2+16=21x+16
При x=2/7 получаем 21*2/7+16=22
3х(3х+7)-(3х+4)(3х-4)
3х(3х+7)-(3х+4)(3х-4)=9x^2+21x-(9x^2-16)=9x^2+21x-9x^2+16=21x+16
При x=2/7 получаем 21*2/7+16=22
3х(3х+7)-(3х+4)(3х-4)