Question 628062
<pre>
f(x) = x<sup>4</sup> + 3x<sup>2</sup> + 5

Synthetic division

To do synthetic division with this polynomial you must insert
zero placeholders for the missing 3rd and 1st powers of x.
of x:

f(x) = x<sup>4</sup> + 0x<sup>3</sup> + 3x<sup>2</sup> + 0x + 5

-3|1  0  3   0   5
  |<u>  -3  9 -36 108</u>
   1 -3 12 -36 <font color="red">113</font>

Answer: f(-3) = <font color="red">113</font>

Check by direct substitution:

f(x) = x<sup>4</sup> + 3x<sup>2</sup> + 5

f(-3) = (-3)<sup>4</sup> + 3(-3)<sup>2</sup> + 5

f(-3) = 81 + 3·9 + 5 = 81 + 27 + 5 = <font color="red">113</font>

So it checks.  The remainder when using a number with synthetic division
will always give the same answer as substituting that number for x directly.

Edwin</pre>