Question

calculeaza 3+6+9+...+90 si 300×299+299×298-598×198

Answer 1

300×299+299×298-598×198 =
299 (300+298)-598×198=
299×598-598×198=
598 (299-198)=
598×101=60398

3+6+9+...+90 = 3 (1+2+...+30) = 3×31×30÷2 = 3×31×15 = 93×15 = 1395

Answer 2

3+6+9+...+90=3(1+2+3+...+30)=3(30x31:2)=3x465=1395

300x299+299x298-598x198=299(300+298)-598x198=299x598-598x198=
598(299-198)=598x101=60398