Question

What is the value of c so that -9 and 9 are both solutions of x2+c=103

Answer 1

`c=22`

Explanation:

Given equation:

`x^2+c=103`

Solutions: -9 and 9

To solve for
`c`

Solution:

The solutions of the equation means
`x=-9` and
`x=9`

We will plugin the solutions in the equation and solve for
`c`

1) when
`x=-9`

`(-9)^2+c=103`

`81+c=103`

Subtracting both sides by 81.

`81+c-81=103-81`

∴
`c=22`

2) when
`x=9`

`(9)^2+c=103`

`81+c=103`

Subtracting both sides by 81.

`81+c-81=103-81`

∴
`c=22`

So, for both solutions we get
`c=22`