Use synthetic division to divide the polynomial (2x^3+11x^2-2x-25) divided by the linear factor (2x+3) and state in the from Q(x)+r(x) where r(x) is the remainder.
Synthetic division is only for division by x-r, where the coefficient
of x is 1. So to use synthetic division when the coefficient of x
is not 1, you must first write the division as a fraction:
Then factor out the coefficient x, in this case 2, in the bottom
(Yes I know you were taught that you couldn't factor anything out of
2x+3, but they meant that you couldn't factor anything out of it without
running into fractions, but you're a big boy or girl now :) and you
can handle fractions. So factor out 2, and get
and put
up with a fraction inside the parentheses:
Now consider that coefficient 2 you factored out on the boottom
as amounting to multiplication by the fraction
:
×
We will do the fraction by synthetic division and
then divide through by 2
-
⃒ 2 11 -2 -25
⃒ -3 -12 21
2 8 -14 -4
This quotient is 2x² + 8x - 14 +
Then we multiply by 1/2 and get:
x² + 4x - 7 +
We can simplify the fraction by multiplying top and bottom
by 2
x² + 4x - 7 +
And then we can just put a minus sign and make the numerator 4
x² + 4x - 7 -
Edwin