Question

已知x=3时 ax+bx的值=3,求代数式（9a+3b)的平方+3a+b的值

Answer 1

ax+bx=3,代入 x=3得：a+b=1

(9a+3b)^2+3a+b=9(3a+b)^2+(3a+b)=(3a+b)(9(3a+b)+1)=(3a+3b-2b)(27a+9b+1)

=(1-2b)(28a+10b)

=(1-2b)(28-18b)