Answer :
1)
y = ax+b
6 = 3a + b
18 = 5a + b
b = 6 - 3a
18 = 5a + 6 - 3a
2a = 12
a = 6
b = 6 - 18
b = -12
f(x) = 6x -12
2)
y = 2
No, because y ≠ 4
x = 2
No, because it's vertical
y = 4
Yes, because x ∈ ℝ and y = 4
x = 4
No, because it's verical
y = ax+b
6 = 3a + b
18 = 5a + b
b = 6 - 3a
18 = 5a + 6 - 3a
2a = 12
a = 6
b = 6 - 18
b = -12
f(x) = 6x -12
2)
y = 2
No, because y ≠ 4
x = 2
No, because it's vertical
y = 4
Yes, because x ∈ ℝ and y = 4
x = 4
No, because it's verical