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If a and b are the odd integers, then th...

If a and b are the odd integers, then the roots of the equation, `2ax^2 + (2a + b)x + b = 0, a!=0`, will be

A

rational

B

irrational

C

non-real

D

none of these

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The correct Answer is:
To solve the quadratic equation \(2ax^2 + (2a + b)x + b = 0\) where \(a\) and \(b\) are odd integers, we will follow these steps: ### Step 1: Identify the coefficients The given quadratic equation is in the standard form \(Ax^2 + Bx + C = 0\), where: - \(A = 2a\) - \(B = 2a + b\) - \(C = b\) ### Step 2: Calculate the discriminant The discriminant \(D\) of a quadratic equation is given by the formula: \[ D = B^2 - 4AC \] Substituting the values of \(A\), \(B\), and \(C\): \[ D = (2a + b)^2 - 4(2a)(b) \] ### Step 3: Expand the discriminant Now we will expand \(D\): \[ D = (2a + b)(2a + b) - 8ab \] \[ D = 4a^2 + 4ab + b^2 - 8ab \] \[ D = 4a^2 - 4ab + b^2 \] \[ D = 4a^2 - 4ab + b^2 = (2a - b)^2 \] ### Step 4: Analyze the discriminant Since \(D = (2a - b)^2\), the discriminant is always non-negative, indicating that the roots are real. ### Step 5: Calculate the roots using the quadratic formula The roots of the quadratic equation can be calculated using the quadratic formula: \[ x = \frac{-B \pm \sqrt{D}}{2A} \] Substituting \(B\) and \(D\): \[ x = \frac{-(2a + b) \pm (2a - b)}{2(2a)} \] ### Step 6: Simplify the roots Now we will simplify the expression: 1. For the negative sign: \[ x_1 = \frac{-(2a + b) - (2a - b)}{4a} = \frac{-2a - b - 2a + b}{4a} = \frac{-4a}{4a} = -1 \] 2. For the positive sign: \[ x_2 = \frac{-(2a + b) + (2a - b)}{4a} = \frac{-2a - b + 2a - b}{4a} = \frac{-2b}{4a} = \frac{-b}{2a} \] ### Conclusion The roots of the equation \(2ax^2 + (2a + b)x + b = 0\) are: \[ x_1 = -1 \quad \text{and} \quad x_2 = -\frac{b}{2a} \] Since both \(a\) and \(b\) are odd integers, \(-1\) is a rational number, and \(-\frac{b}{2a}\) is also rational because the product of two odd integers is odd, and dividing an odd integer by an even integer (which \(2a\) is) yields a rational number. Thus, the roots of the equation are rational.
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