Question

d) 5x+5y+5z daca x+y+z=-9, x,y,z numere intregi.

Answer 1

5x + 5y + 5z = ?

x + y + z = -9    |·5 (inmultim toata relatia cu 5)

5 · x + 5 · y + 5 · z = -9 · 5

5x + 5y + 5z = -45

Answer 2

x+y+z=-9

5x+5y+5z=

=5×(x+y+z)

=5×(-9)

= -45