Question

四道二元一次方程,用代人法解答,

Answer 1

(1)将一式代入二式得2b+3=3b+20解得b=-17,a=-31

(2)将二式代入一式得6y-7-y=13解得y=4,x=17

(3)由一式得x=4+y代入二式得16+4y+2y=-1解得y=-17/6,x=7/6

(4)由一式得y=5x-110代入二式得45x-990-x=110解得x=25,y=15