Question

x³ + 3x² + 2x - 210=0
solve the quadratic equation​

Answer 1

Answer: X = 5

x(x + 1)(x + 2) = 210

Use FOIL on the binomial terms.

x(x2 + 3x + 2) = 210

Distribute the x to the terms in parenthesis.

x3 + 3x2 + 2x = 210

Subtract 210 to both sides of the equation to make the right side equal to zero.

x3 + 3x2 + 2x - 210 = 0

Use synthetic division to find a quadratic factor.

5 |  1       3        2          -210

              5       40          210

_______________________________

     1       8       42            0

So you have

(x - 5)(x2 + 8x + 42) = 0

One of your solutions is     x=5