Check whether $7+ 3x$ is a factor of $3x^2 + 7x$.


Given :

$P(x) = 3x^2+7x$, $7+ 3x$.


To do :

We have to check whether $7+ 3x$ is a factor of P(x).


Solution :


Factor Theorem:

The factor theorem states that if p(x) is a polynomial of degree n > or equal to 1 and ‘a’ is any real number, then $x-a$ is a factor of $p(x)$, if $p(a)=0$.


We have to equate $7+3x = 0$

$3x+7 = 0$

$3x = -7$

$x = \frac{-7}{3}$

Therefore,

$P( \frac{-7}{3}) = 3( \frac{-7}{3})^2+7( \frac{-7}{3})$

               $= 3(\frac{49}{9}) - \frac{49}{3}$
 
               $= \frac{49}{3}- \frac{49}{3}$
   
                $= 0$

Therefore,  $7+ 3x$ is a factor of $3x^2 + 7x$.

Updated on: 10-Oct-2022

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