# Math Help - polynomial help please

I have to factor these polynomials
64x^3+343
400x^2-25
x^4+8x^2-9
2x^3-3x^2+4x-6

2. $
\begin{gathered}
400x^2 - 25 = \left( {20x - 5} \right)\left( {20x + 5} \right) \hfill \\
2x^3 - 3x^2 + 4x - 6 = \left( {x - 1.5} \right)\left( {2x^2 + 4} \right) \hfill \\
\end{gathered}
$

3. first one use the sum of two cubes formula.

$a^3+b^3 = (a+b)(a^2-ab+b^2)$

it will be helpful to write $64x^3+343
$
as $
(4x)^3 + 7^3$

for the second one, use the difference of two squares formula $a^2 - b^2 = (a-b)(a+b)$

it may be helpful to write $400x^2-25
$
as $(20x)^2-5^2$

the third one, first factor by inspection.

$x^4+8x^2-9 = (x^2 -1)(x^2 +9)$

then use the difference of two squares formula on the first factor

For the last one, are you familiar with synthetic division ? if i told you (2x-3) was a factor could you factor it ?

4. ## =]

thanks for the helppp!