The percent error is 29%. I posted the equation for percent error on your other question.
Whats the problem? i cant solve it w/o the problem doll
According to Vieta's Formulas, if

are solutions of a given quadratic equation:
Then:
is the completely factored form of

.
If choose

, then:

So, according to Vieta's formula, we can get:

But

:
(X-7)(x-7)
Hope this is what you're looking for!