Question

Analyze the steps taken to solve for x. Identify the error and explain why you think the error was made. Then, correctly solve for x. 4x + 9 = 16

divide both sides by 4 to get x + 9 = 4
then subtract both sides by 9 to get: x + -5

Answer 1

see explanation

Explanation:

4x + 9 = 16

the error being made is that on dividing both sides by 4 all terms must be divided by 4.

to obtain x + 9 = 4 from 4x + 9 = 16

the term 9 has not been divided by 4

correct solution is

4x + 9 = 16 ( divide through by 4 )

x +
`(9)/(4)` = 4 ( each term being divided by 4 )

x +
`(9)/(4)` = 4 ( subtract
`(9)/(4)` from both sides )

x = 4 -
`(9)/(4)` =
`(16)/(4)` -
`(9)/(4)` =
`(7)/(4)` = 1.75

or

4x + 9 = 16 ( subtract 9 from both sides )

4x = 7 ( divide both sides by 4 )

x =
`(7)/(4)` = 1.75