急急急,数学题...

2倍根号2+根号8-根号50
=2√2+√(2x2x2)-√(5x5x2)
=2√2+2√2-5√2
=4√2-5√2
=-√2
96÷2倍根号3×根号2
=96x(1/2√3)x√2
=96x(√3/6)x√2
=16x√稿御3x√键信岩2
=16x√6
=39.191835884530849571156545195294
4÷(根号5+1)
=4x[1/(√5+1)]
=4x[(√5-1)/(5-1)]
=4x[(√5-1)/4]
=√坦逗5-1
=1.2360679774997896964091736687313
306=4/3πR三次方
R=³√73.089171974522292993630573248408
=4.1810402387747519798990656539058
已知An=(-1)^n+1
n=1,A1=0
n=2,A2=2
n=3, A3=0
2写出A1+A2+A3+A4+A5+A6……+An
=0+2+0+2+0+2……+An
=2x[n/2]
注：方括号[]代表取整

0 1 2 A1=-1 N加1

n=1 ,A1=0 n=2 ,A2=2 n=3 ,A3=0n=4, A4=2
当n为锋困奇数时A1+A2+A3+A4+A5+A6…银握念…+An =n-1
当n为偶数皮举时A1+A2+A3+A4+A5+A6……+An =n