7/15m = P+1
代入Q=m的平方+715m,
Q=m的平方+P+1
那就改一下
Q-P=m²-8/15m-7/15m+1
=m²-m+1
=m²-m+1/4+3/4
=(m-1/2)²+3/4≥3/4>0
所以Q>P