Question

determinati valoarea numerica a expresiei -3x+5y

a) x=2,y=6
b)x=0,y=8
c)x=5,y=1
d)x=-3,y=-5
e)x=7,y=-9
f)x=-2,y=12

Answer 1

a) -3×2 + 5×6= -6 +30 = 24
b)-3×0 +5×8 = 0+40=40
c)-3×5 + 5×1=-15 +5=20
d)-3×(-3) + 5×(-5)=9+(-25) =-16
e) -3×7 + 5×(-9)= -21 + (-45) =66
f)-3×(-2) + 5×12=6+60=66

Answer 2

Deci :-3x+5y
a)x=2
y=6
Inlocuim:
-3•2+5•6=-6+30=24

b)x=0
y=8
-3•0+5•8=-0+40=40

c)x=5
y=1
-3•5+5•1=-15+5=-10

d)x=-3
y=-5
-3•(-3)+5•(-5)=+9-25=16

e)x=7
y=-9
-3•7+5•(-9)=-21-45=-66

f)x=-2
y=12
-3•(-2)+5•12=+6+60=66