f x 3 x 7 solve f x 12Solutionif it is f x 3 x 7

f ( x ) = 3 x + 7 solve f ( x ) = 12

Solution

if it is

f ( x ) = 3 x + 7

given f ( x ) = 12

equate

3 x + 7 =12

3 x   =12-7

3 x   =5

x   =5/3

squaring on both sides

( x)²=(5/3)²

x=25/9

==============================

if it is

f ( x ) = 3 (x + 7)

given f ( x ) = 12

equate

3 (x + 7) =12

(x + 7) =12/3

(x + 7) =4

squaring on both sides

((x + 7))²=4²

x+7 =16

x=16-7

x =9