Question

calculeaza,folosind factorul comun: a) 73x538-73x500-73x37 ;b) 3+6+9+...+90; c) 300x299+299x298-598x198.

Answer 1

a) 73×538-73×500-73×37=
= 73×(538-500-37) =
= 73×1= 73

b) 3+6+9+...+90=
=3×(1+2+3+...+30)=
=3×30×31÷2=
=3×465=
=1395

c) 300×299 + 299×298 - 598×198 =
= 300×299 +299×298 - 2×299×198 =
= 299×(300+298-2×198) =
= 299×(300+298-396) = 
= 299×202 = 
= 60398

Answer 2

a) 73(538-500-37)= 73 * 1 = 73
b) 3(1+2+3+...+30) = 3*465= 1395
c) 299(300+298-2*198) = 299*202=60398
Sper ca e corect !