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If quadratic equation ax^2+bx+c=0 does n...

If quadratic equation `ax^2+bx+c=0` does not have real roots, then which of the following may be false (a) `a(a-b+c) gt 0` (b) `c(a- b+c)>0` e) `b(a- b+c) gt 0` (d) `a +b+c) (a-b+c)gt0`

A

`a(a-b+c)gt 0`

B

`c (a-b +c) gt 0`

C

`b (a-b+c) gt 0`

D

`(a+b+c) (a-b+c) gt 0`

Text Solution

AI Generated Solution

The correct Answer is:
To determine which of the given statements may be false when the quadratic equation \( ax^2 + bx + c = 0 \) does not have real roots, we need to analyze the implications of the condition that the quadratic has no real roots. This occurs when the discriminant \( D = b^2 - 4ac < 0 \). Let's analyze each option step by step: ### Step 1: Analyze the Condition for No Real Roots The condition for the quadratic equation \( ax^2 + bx + c = 0 \) to not have real roots is: \[ D = b^2 - 4ac < 0 \] This implies that \( b^2 < 4ac \). ### Step 2: Evaluate Each Option **Option (a): \( a(a - b + c) > 0 \)** 1. If \( a > 0 \): - For \( a - b + c > 0 \): This can be true if \( b^2 < 4ac \) holds. - Thus, \( a(a - b + c) > 0 \) can be true. 2. If \( a < 0 \): - For \( a - b + c < 0 \): This can also hold true under certain conditions. - Thus, \( a(a - b + c) > 0 \) can also be true. **Conclusion**: This option can be true in both cases. --- **Option (b): \( c(a - b + c) > 0 \)** 1. If \( c > 0 \): - For \( a - b + c > 0 \): This can hold under certain conditions. - Thus, \( c(a - b + c) > 0 \) can be true. 2. If \( c < 0 \): - For \( a - b + c < 0 \): This can also hold true under certain conditions. - Thus, \( c(a - b + c) > 0 \) can also be true. **Conclusion**: This option can be true in both cases. --- **Option (c): \( b(a - b + c) > 0 \)** 1. If \( b > 0 \): - For \( a - b + c > 0 \): This can hold true under certain conditions. - Thus, \( b(a - b + c) > 0 \) can be true. 2. If \( b < 0 \): - For \( a - b + c < 0 \): This can also hold true under certain conditions. - Thus, \( b(a - b + c) > 0 \) can also be true. 3. However, since \( b \) can take any value (positive, negative, or zero), we cannot definitively conclude that this expression will always be positive or negative. **Conclusion**: This option may be false depending on the value of \( b \). --- **Option (d): \( (a + b + c)(a - b + c) > 0 \)** 1. If both \( a + b + c > 0 \) and \( a - b + c > 0 \): This can hold true under certain conditions. 2. If both \( a + b + c < 0 \) and \( a - b + c < 0 \): This can also hold true under certain conditions. **Conclusion**: This option can be true in both cases. ### Final Conclusion The option that may be false is: **(c) \( b(a - b + c) > 0 \)**
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VK JAISWAL ENGLISH-QUADRATIC EQUATIONS -EXERCISE (SUBJECTIVE TYPE PROBLEMS)
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