x的四次方减y的四次方
=(x^2+y^2)(x^2-y^2)
=(x^2+y^2)(x+y)(x-y)
x^4-y^4
=(x^2)^2-(y^2)^2 (逆山中局用 幂的逗让乘方 法则)
=(x^2+y^2)(x^2-y^2) (平方差公式)
=(x^2+y^2)(x+y)(x-y) (平方培仿差公式)
x^4-y^4=(x^2)^2-(Y^2)^2=(x^2-y^2)(x^2+y^2)
=(x+y)(x-y)(x^2+y^2)
=(x^2+y^2)(x^2-y^2)
=(x^2+y^2)(x+y)(x-y)
X4-Y4
=(X2+Y2)(X2-Y2)
=(X2+Y2)(X+Y)(X-Y)