X ^ 2 +2 X +1 ppm的X +1÷2×2 ppm的X +3
=(X + 1)/(x +1)2×2(X +1)/(x +3)
= 2 /(x +3)
2(2X +2?三分之二XY) - (x ^ 2-Y ^ 2 ppm的X ^ 2 + Y ^ 2)
> =(xy)的/ 2(x + y的) - (X 2 + Y 2)/(x + y的)(xy)的
= [(xy)的2 -2(X 2 + Y 2)] / 2(x + y的)(xy)的]
= - (×2 +2 XY + Y 2)/ 2(X + y)的值(xy)
= - (+ Y)2/2 (X + Y
3.X ^ 2 +4)(XY)
=(X + Y)/(2Y-2X)+4百万分之x ^ 2-1÷(X 1)* x-1的ppm的χ^ 2 +3 X +2
=第(x +1)(x-1的)/(×2)2×1 /(×1)×(+ 1)第(x +2)/(x-1的)
=第(x +1)/(×2)
4. (M + N)(百万元)-2(百万元)^ 2
= M2-N 2 -2(M2-2?MN + N 2)
= 2 +4 MN-3N 2 / a>
请采纳,问题又来了帮助