Question

化简或求值 -3(5x-7y)+6(2x-4y) 和a-(2a-7b)+3(a-2b),其中a=-2,b=-100

Answer 1

-3(5x-7y)+6(2x-4y) 和 a-(2a-7b)+3(a-2b),其中a=-2,b=-100

=-15x+21y+12x-24y =a-2a+7b+3a-6b

=-3x-3y =2a+b

a=-2,b=-100

2a+b=2*(-2)+(-100)=-4-100=-104