2a(1+x%)²-a(1-x%)²
问题描述:
2a(1+x%)²-a(1-x%)²
答
2a(1+x%)²-a(1-x%)²
=a*[2(1+2*x%+ x%*x%)- (1- 2*x%+x%*x%)]
=a*[2+4*x%+ 2(x%)²- 1 + 2*x%-(x%)²]
=a*[1+6*x%+ (x%)²]