if f(x)=3x find (i)f(1) (ii) f(3)

if f(x)=3x find (i)f(1) (ii) f(3) (iii) f(4) (iv) f(6)

$$\mathbf{~ f(x) = 3\cdot x ~}$$

(i) f(1) 

Set x = 1

$$\small{\text{$
f(1) = 3\cdot 1 = 3
$}}$$

(ii) f(3)

Set x = 3

$$\small{\text{$
f(3) = 3\cdot 3 = 9
$}}$$

(iii) f(4)

Set x = 4

$$\small{\text{$
f(4) = 3\cdot 4 = 12
$}}$$

(iv) f(6)

Set x = 6

$$\small{\text{$
f(6) = 3\cdot 6 = 18
$}}$$