1.858²-558²2.202²+202×196+98²3.x²-2xy+y²-94.(x-4)(x+1)+3x
问题描述：
1.858²-558²
2.202²+202×196+98²
3.x²-2xy+y²-9
4.(x-4)(x+1)+3x
答
858²-558²
=(858-558)(858+558)
=300×1416
=424800
202²+202×196+98²
=(202+98)²
=300²
=90000
x²-2xy+y²-9
=(x-y)²-9
=(x-y-3)(x-y+3)
(x-4)(x+1)+3x
=x²-3x-4+3x
=x²-4
=(x-2)(x+2)
答
1. 858²-558²=(858-558)*(858+558)=300*1416=424800
2. 202²+202×196+98²=202²+2×202×98+98²=(202+98)²=300²=90000
3. x²-2xy+y²-9=(x-y)²-9=(x-y+3)(x-y-3)
4. (x-4)(x+1)+3x=x²-3x-4+3x=x²-4=(x+2)(x-2)
答
1.858²-558²=(858+558)(858-558)=1416*300=4248002.202²+202×196+98²=(202+98)²=900003.x²-2xy+y²-9=(x-y)²-9=(x-y+3)(x-y-3)4.(x-4)(x+1)+3x=x²-3x-4+3x=x²-4=...
答
1=(858-558)*(858+558)
2=(202+98)^2
3=(x-y)^2-9=(x-y-3)*(x-y+3)
4=x^2-3x-4+3x=(x-2)(x+2)