👤

Ex. 11
Va roooggg!
Dau coroana!


Ex 11Va Roooggg Dau Coroana class=

Răspuns :

a) 2S=90×91:2 =4095 b)2×1+2×2+2×3+.....+2×100 2×(1+2+3+.....+100)= 2×[100×(100+1)]÷2= 2×100×101:2= =10100 c)3+7+11+....+43 3+(3+4×1)+(3+4×2)+....+(3+4×10) =3×10+4×[10×(10+1)÷2] =30+4×10×11÷2 =30+220 =250