Question

Am nevoie de ajutorul vostru cu prioritate nr 46.multumesc

Answer 1

46)
formula  1+2+3..+n=n(n+1)/2
a) 6+12+18+...+216=6×(1+2+3+...+36)=6×36×37/2=3996
b)10+20+30+...+2020=10×(1+2+3+...+202)=10×202×203/2=205030
c)2012×2011-2011×2010+2011×2009-2008×2011=
=2011(2012-2010+2009-2008)=2011(2+1)=2011×3=6033
d)(2+4+6+...+2012)-(4+8+12+...+2012)-503×1005=
=2×(1+2+3+...+1006)-4×(1+2+3+...+503)-503×1005=
=2×1006×1007/2-4×503×504/2-503×1005=
=1006×1007-1006×504-503×1005=
=1006×(1007-504)-503×1005=
=1006×503-503×1005=
=503×(1006-1005)=503