Question

数学王子高斯从小就善于观察和思考

Answer 1

1+2+3...+n① n个数,求和 n(n+1)/2 2+3+4...n+1② 也是n个数,求和 n(2+n+1)/2①+②=168(n(n+1)+n(n+3))/2 =n(n+2)=168n=12另解:3+5+7+…+(2n+1)有n项3+5+7+…+(2n+1)= n(3+2n+1)/2=n(n+2)=168 n=12