Question

Dacă a+b=35 si b+c=17 calculează.:
a) a+2b+c
b) a-c
c) 2a+5b+3c
d) 3a+b-2c

Answer 1

a+b= 35
b+c = 17

a) a+2b+c = 35 + 17 = 52

b) a+b - b - c = 35 - 17
a - c = 18

c) a + b = 35 |×2
2a+2b = 70 (1)

b + c = 17 |×3
3b + 3c = 51 (2)
adunam (1) si (2)
2a + 5b + 3c = 70 + 51 = 121

d) a+b = 35 |×3
3a+3b = 105 (1)

b + c = 17 |×2
2b + 2c = 34 (2)

(1) - (2) = 3a +b - 2c = 105 -34 =71