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mathematicinductionProve,bymathematicinductiona)1*2+2*3+3*4+.+n(n+1)=1/3*n(n+1)(n+2)b)henceorotherwisefindthevalueof1+(1+2)+(1+2+3)+...+(1+2+3+.+100)

题目详情
mathematic induction
Prove,by mathematic induction
a)1*2+2*3+3*4+.+n(n+1)=1/3*n(n+1)(n+2)
b)hence or otherwise find the value of
1+(1+2)+(1+2+3)+...+(1+2+3+.+100)
▼优质解答
答案和解析
a)first:1*2=1/3*1*2*3=22nd:if 1*2+2*3+3*4+.+n(n+1)=1/3*n(n+1)(n+2) then:1*2+2*3+3*4+.+n(n+1)+(n+1)(n+2)=1/3*n(n+1)(n+2)+(n+1)(n+2)=(n+1)(n+2)(n/3+1)=1/3(n+1)(n+2)(n+3)so:1*2+2*3+3*4+.+n(n+1)=1/3*n(n+1...