Question

Use synthetic division to show that the number given to the right of the equation is a solution of the equation. Then solve the polynomial equation.
2x^(3)+x^(2)-8x-4=0; 2

Answer 1

Answer:

$x = 2 \: or \: x = - 2 \: or \: x = - \frac{1}{2}$

Step-by-step explanation:

The given polynomial equation is

$2 {x}^{3} + {x}^{2} - 8x - 4 = 0$

We perform the synthetic division as shown in the attachment by dividing by x-2.

This gives a remainder of 0 and a quotient of

$2 {x}^{2} + 5x + 2$

This means the polynomial equation becomes:

$(x - 2)(2 {x}^{2} + 5x + 2) = 0$

We factor the quadratic term by splitting the middle term;

$(x - 2)(2 {x}^{2} + 4x +x + 2) = 0$

$(x - 2)(2 x(x+ 2) +1(x + 2) )= 0$

Collect common factors again:

$(x - 2)((x+ 2)(2x + 1) = 0$

The solution is:

$x = 2 \: or \: x = - 2 \: or \: x = - \frac{1}{2}$