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Find the roots of x3 - 2x2 - 5x + 6 = 0...

Find the roots of x3 - 2x2 - 5x + 6 = 0

A.

1, -2, 3

B.

1, 2, -3,

C.

-1, -2, 3

D.

-1, 2, -3

Correct answer is A

Equation: x3 - 2x2 - 5x + 6 = 0.

First, bring out an which is the coefficient of x3 = 1.

Then, a0 which is the coefficient void of x = 6.

The factors of an = 1; The factors of a0 = 1, 2, 3 and 6.

The numbers to test for the roots are ±(a0an).

= ±(1,2,3,6).

Test for +1: 13 - 2(12) - 5(1) + 6 = 1 - 2 - 5 + 6 = 0.

Therefore x = 1 is a root of the equation.

Using long division method, x32x25x+6x1 = x2 - x - 6.

x2 - x - 6 = (x - 3)(x + 2).

x = -2, 3.

The roots of the equation = 1, -2 and 3.