Question

C, e, f dau coroană cine ma ajuta la acest ex c, e, f

Answer 1

f)8x+8•2x+8•3x+......+8•12x=6240 8•(×+2x+3x+.......+12x)=6240 x•(1+2+3+.....+12)=6240:8 x•78=780 x=780:78 x=10

Answer 2

X x ( 1 + 2+ ....+ 20) = 2100
X x [20 x (20 + 1) : 2 = 2100
X x (20 x 21 : 2) = 2100
210 X = 2100
X = 10


X x (5 + 10 + ... +100) = 4200
X x 100 x (100 + 5):5 = 4200
X x 100 x 21 = 4200
2100 X = 4200
X = 2