Question

Daca a+b=20 si b+c=30,calculati 3a+7b+4c si 7a+3b-4c​

Answer 1

Explicație pas cu pas:

a+b=20

b+c=30

▪︎3a+7b+4c = 3a + 3b + 4b + 4c = 3(a+b) + 4(b+c) = 3×20 + 4×30 = 60 + 120 = 180

▪︎7a+3b-4c = 7a + 7b - 4b - 4c = 7(a+b) - 4(b+c) = 7×20 - 4×30 = 140 - 120 = 20