If A=6+9x^2 and B=7+3x,the what is A in terms of

问题描述:

If A=6+9x^2 and B=7+3x,the what is A in terms of

答:A=B^2-14B+55
译:若A=6+9x^2,B=7+3x,则A用B如何表示?
以x为中间量,过渡转化,以B表示A
∵B=3x+7
∴x=(B-7)/3
代入A=9x^2+6得,A=9【(B-7)/3】^2+6=...(化简得)=B^2-14B+55