Question

若代数式x^2-5x的值为-4,则代数式x^2-3x+3

Answer 1

x^2-5x=-4

x^2-5x+4=0

(x-4)(x-1)=0

x=4 x=1

当x=4时

x^2-3x+3=16-12+3=7

当x=1时

x^2-3x+3=1-3+3=1