MHB What Mistake Was Made in This Polynomial Long Division?

[shamieh]

rewrite using polynomial long division

$$\frac{x^3 + 4x^2 + 3}{x+4}$$

so I did $$x+4 \sqrt{x^3 + 4x^2 + 0x + 3}$$

and got $$x^2 + 1 - \frac{1}{x+4}$$

What am i doing wrong? How is that incorrect?

 

[Deveno]

I think you made an error in your first subtraction:

$x^3 + 4x^2 + 3 - (x + 4)x^2 = x^3 + 4x^2 + 3 - x^3 - 4x^2 = 3$.

 

[soroban]

Hello, shamieh!

Rewrite using polynomial long division: $$ \;\;\frac{x^3 + 4x^2 + 3}{x+4}$$

[math]\begin{array}{cccccccccc}
&&&& x^2 & + & 0x & + & 0 \\
&& --&--&--&--&--&--&-- \\
x+4 & ) & x^3 & + & 4x^2 &+&0x& + & 3 \\
&& x^3 & + & 4x^2 \\
&& --&--&-- \\
&&&& 0x^2 &+& 0x \\
&&&& 0x^2 &+& 0x \\
&&&& --&--&--&--\\
&&&&&& 0x &+& 3 \\
&&&&&& 0x &+& 0 \\
&&&&&& --&--&-- \\
&&&&&&&& 3 \end{array}[/math]
Answer: [math]\;x^2 + \frac{3}{x+4}[/math]