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If a gt 2, then the roots of the equatio...

If `a gt 2`, then the roots of the equation `(2-a)x^(2)+3ax-1=0` are

A

one positive and one negative

B

both negative

C

both positive

D

both imaginary

Text Solution

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The correct Answer is:
To solve the problem, we need to analyze the quadratic equation given by: \[ (2 - a)x^2 + 3ax - 1 = 0 \] ### Step 1: Identify the coefficients The coefficients of the quadratic equation can be identified as follows: - \( A = 2 - a \) (coefficient of \( x^2 \)) - \( B = 3a \) (coefficient of \( x \)) - \( C = -1 \) (constant term) ### Step 2: Determine the nature of the roots To determine the nature of the roots of a quadratic equation, we can use the discriminant \( D \), which is given by: \[ D = B^2 - 4AC \] Substituting the coefficients into the discriminant formula, we get: \[ D = (3a)^2 - 4(2 - a)(-1) \] ### Step 3: Simplify the discriminant Now, let's simplify the expression for \( D \): \[ D = 9a^2 + 4(2 - a) \] \[ D = 9a^2 + 8 - 4a \] \[ D = 9a^2 - 4a + 8 \] ### Step 4: Analyze the discriminant Next, we need to check the sign of the discriminant \( D \). Since \( a > 2 \), we can analyze the quadratic \( 9a^2 - 4a + 8 \). The discriminant of this new quadratic can be calculated as follows: \[ D' = (-4)^2 - 4 \cdot 9 \cdot 8 \] \[ D' = 16 - 288 = -272 \] Since the discriminant \( D' < 0 \), the quadratic \( 9a^2 - 4a + 8 \) does not have real roots, which means it is always positive for all \( a \). ### Step 5: Conclusion about the roots Since \( D > 0 \) for \( a > 2 \), it indicates that the original quadratic equation has two distinct real roots. ### Final Answer Thus, if \( a > 2 \), the roots of the equation \( (2 - a)x^2 + 3ax - 1 = 0 \) are **real and distinct**. ---
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