Question

1la a 2 a +2la a 2 a + 3 la a 2 a....... +n la a 2 a=n(n+1)(2n+1)supra 6​

Answer 1

Răspuns:

${1 }^{2} + {2}^{2} + {3}^{2} + 6 {}^{2} + {9}^{2} =$

n(n+1)(2n+1)supra 6 =1+4+9+36+81=131 supra 6 si scoatem intregii