(6t-2)/2-(2t+1)/2=(10t+1)/5等于多少?

题目

(6t-2)/2-(2t+1)/2=(10t+1)/5等于多少?
用两种解答方法

答案

原式=15x^2-18x+9+3x^2-19x+31-8x
=18x^2-45x+40
=9（2x^2-5x）+40
=0+40
=40
原式=5x²-3xy-y²-11xy-4x²+2y²
=x²+y²-14xy
=7-14×(2)
=35