1.

Solve the equation \( x^{3}-3 x^{2}+4=0 \), given that two of its roots are equal.

Answer»

Given equation is x3 - 3x2 + 4 = 0

\(\because\) x = -1 satisfies the equation.

(Because, (-1)3 - 3(-1)2 + 4 = -1 - 3 + 4 = -4 + 4 = 0)

\(\therefore \) (x + 1) is a factor of x3 - 3x2 + 4.

Now,

since x3 - 3x2 + 4 = 0

⇒ (x + 1) (x2 - 4x + 4) = 0

⇒ (x + 1) (x - 2)2 = 0

⇒ x = -1, 2, 2

Hence, roots of given equation are -1, 2, 2.



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