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Let a, b, c be non zero numbers such tha...

Let a, b, c be non zero numbers such that
`int_(0)^(3)sqrt(x^(2)+x+1)(ax^(2)+bx+c)dx=int_(0)^(5)sqrt(1+x^(2)+x)(ax^(2)+bx+c)dx`. Then the quadratic equation `ax^(2)+bx+c=0` has

A

no root in (0, 3)

B

at least one root in (3, 5)

C

a double root in (0, 3)

D

two imaginary roots

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The correct Answer is:
To solve the problem, we start with the given equation: \[ \int_{0}^{3} \sqrt{x^2 + x + 1} (ax^2 + bx + c) \, dx = \int_{0}^{5} \sqrt{x^2 + x + 1} (ax^2 + bx + c) \, dx \] Let \( f(x) = \sqrt{x^2 + x + 1} (ax^2 + bx + c) \). ### Step 1: Set up the equation From the equality of the two integrals, we have: \[ \int_{0}^{3} f(x) \, dx = \int_{0}^{5} f(x) \, dx \] ### Step 2: Rearranging the equation This implies: \[ \int_{3}^{5} f(x) \, dx = 0 \] ### Step 3: Analyze the integral Since \( f(x) \) is continuous (as it is a product of continuous functions), the integral being zero suggests that the function \( f(x) \) must change sign over the interval \([3, 5]\). ### Step 4: Apply Rolle's Theorem By Rolle's Theorem, since \( f(x) \) is continuous on \([3, 5]\) and differentiable on \((3, 5)\), there exists at least one \( c \in (3, 5) \) such that: \[ f(c) = 0 \] ### Step 5: Setting the quadratic to zero Thus, we have: \[ \sqrt{c^2 + c + 1} (ac^2 + bc + c) = 0 \] Since \( \sqrt{c^2 + c + 1} \neq 0 \) for all \( c \), we must have: \[ ac^2 + bc + c = 0 \] ### Step 6: Factor out \( c \) This can be factored as: \[ c(ac + b + 1) = 0 \] Since \( c \) is non-zero (as given in the problem), we have: \[ ac + b + 1 = 0 \] ### Step 7: Conclusion about roots This means that the quadratic equation \( ax^2 + bx + c = 0 \) must have at least one root in the interval \((3, 5)\). Therefore, we conclude that the quadratic equation has roots. ### Final Result The quadratic equation \( ax^2 + bx + c = 0 \) has at least one root in the interval \((3, 5)\). ---
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