Question

arata ca nr a=17+17x2+17x3+17x4+...+17x17 este patrat perfect

Answer 1

$a=17\cdot(1+2+3+4+\ldots+17)=17\cdot\dfrac{(1+17)\cdot17}{2}=\\=9\cdot17^2=3^2\cdot17^2=(3\cdot17)^2=51^2,\;care\;este\;p\breve{a}trat\;perfect.$

Green eyes.