Question

daca x + 2 y=17 si y-3z= 4 calculati : a) x+3y-3z = b)2x+5y-3z = c)(3x+6y)+(2y-6z) d) 2x+4y) *(x+4y-6z)

Answer 1

x+2y=17
x=17-2y
y-3z=4
-3z=4-y
a) x+3y-3z=
17-2y+3y+4-y=21
b) 2x+5y-3z=
2(17-2y) +5y+4-y=
34-4y+5y+4-y=38
c) (3x+6y)+(2y-6z)=
(3(17-2y)+6y)+(2y+8-2y)=
(34-6y+6y)+8=42
d) (2x+4y)*(x+4y-6z)=
(34-4y+4y)*(17-2y+4y+8-2y)=34*25