Vaaa rog din suflet am nevoie repede

Răspuns:

a) x=4

b) x=29

c) x=28

Explicație pas cu pas:

a) x/18=2/9

9x=18×2

9x=36

x=36:9=4

b)(x-8)/12=7/4

4(x-8)=12×7

4x-32=84

4x=84+32

4x=116

x=116:4=29

c) (x-7)/(1+2+3+....+13)=3/13

1+2+3+....+13=

13×(13+1):2=

13×14:2=

13×7=91

(x-7)/91=3/13

13(x-7)=91×3

13x-91=273

13x=273+91

13x=364

x=364:13=28

Răspuns:

a) x×9=2×18

9x=36

x=36÷9

x=4

b)(x-8)×4=7×12

(x-8)=84÷4

x-8=21

x=21+8

x=30

c)(x-7)×13=(1+2+3+...+13)×3

(x-7)×13=[(13×14)÷2]×3

(x-7)×13=(182÷2)×3

(x-7)×13=91×3

x-7=273÷13

x=21+7

x=28