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`a, b, c, in R, a ne 0` and the quadratic equation `ax^(2) + bx + c = 0` has no real roots, then which one of the following is not true?

A

`a + b + c gt 0`

B

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

C

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

D

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

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the conditions under which the quadratic equation \( ax^2 + bx + c = 0 \) has no real roots. This occurs when the discriminant \( D \) is less than zero. The discriminant is given by: \[ D = b^2 - 4ac \] Since we are given that \( D < 0 \), we can conclude that: \[ b^2 - 4ac < 0 \implies b^2 < 4ac \] This means that \( ac \) must be positive, as \( b^2 \) is always non-negative (since it is a square). Next, we will analyze the options provided in the question to determine which one is not true. ### Step 1: Analyze the options 1. **Option A: \( a + b + c > 0 \)** This option does not necessarily hold true. For example, if \( a = 1 \), \( b = -3 \), and \( c = 2 \), we have: \[ a + b + c = 1 - 3 + 2 = 0 \] This shows that \( a + b + c \) can be zero, which means it is not always greater than zero. 2. **Option B: \( a(a + b + c) > 0 \)** Since \( a \) is not equal to zero, if \( a + b + c > 0 \), then this option holds true. However, if \( a + b + c \leq 0 \), this option may not hold. 3. **Option C: \( ac(a + b + c) > 0 \)** Since we established that \( ac > 0 \), if \( a + b + c > 0 \), then this option is true. However, if \( a + b + c \leq 0 \), this option may not hold. 4. **Option D: \( c(a + b + c) > 0 \)** This option also depends on the sign of \( c \) and \( a + b + c \). If \( c > 0 \) and \( a + b + c > 0 \), then this option holds true. ### Conclusion From the analysis, we find that: - **Option A** is not necessarily true since \( a + b + c \) can be zero or negative. - **Options B, C, and D** can hold true under certain conditions. Thus, the answer to the question is: **Option A is not true.**

To solve the problem, we need to analyze the conditions under which the quadratic equation \( ax^2 + bx + c = 0 \) has no real roots. This occurs when the discriminant \( D \) is less than zero. The discriminant is given by: \[ D = b^2 - 4ac \] Since we are given that \( D < 0 \), we can conclude that: ...
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OBJECTIVE RD SHARMA ENGLISH-QUADRATIC EXPRESSIONS AND EQUATIONS -Chapter Test
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  11. If a, b, c are positive real numbers, then the roots of the equation a...

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