Question

Determina termenul necunoscut din egalitatile urmatoare: a)(3xa+5)x5-3=292 b)(b-5)x2=30 c)(c-17)x3+15=45 d)[2x(d-30)-45]x3=165 Metoda mersului invers

Answer 1

a) (3xa+5)x5-3=292
(3xa+5)x5=292+3
3xa+5=295:5
3xa=59-5
a=54/3
a=18

b) (b-5)x2=30
b-5=30/2
b=15+5
b=20

c) (c-17)x3+15=45
(c-17)x3=45-15
c-17=30/3
c=10+17
c=27

d) [2x(d-30)-45]x3=165
2x(d-30)-45=165/3
2x(d-30)=55+45
d-30=100/2
d=50+30
d=80

Answer 2

a)
(3xa+5)x5-3=292
(3xa+5)x5=292+3
(3xa+5)x5=295
3xa+5=295:5
3xa+5=59
3xa=59-5
3xa=54
a=54:3
a=18

b)
(b-5)x2=30
b-5=30:2
b-5=15
b=15+5
b=20

c)
(c-17)x3+15=45
(c-17)x3=45-15
(c-17)x3=30
c-17=30:3
c-17=10
c=10+17
c=27

d)
[2x(d-30)-45]x3=165
2x(d-30)-45=165:3
2x(d-30)-45=55
2x(d-30)=55+45
2x(d-30)=100
d-30=100:2
d-30=50
d=50+30
d=80