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Which of the following is false? (i) I...

Which of the following is false?
(i) If only the positive values of x are taken, the quadratic graph does not intersect the K-axis.
(ii) if only negative values are taken, the quadratic graph does not intersect the X-axis.
(iii)The intercept of X-axis can be known when we substitute x =0, in the quadratic function.
(iv)There can be minimum zero and maximum two x-intercepts .

A

(A) (i) and (iv)

B

(B) (i),(ii),(iii)and (iv)

C

(C) (i),(ii) and (iii)

D

(D) none of these

Text Solution

AI Generated Solution

The correct Answer is:
To determine which of the statements is false, we will analyze each statement one by one based on the properties of quadratic equations. ### Step 1: Analyze Statement (i) **Statement (i):** If only the positive values of x are taken, the quadratic graph does not intersect the x-axis. - A quadratic function is given by \( y = ax^2 + bx + c \). - The graph intersects the x-axis where \( y = 0 \), which means we need to find the roots of the equation \( ax^2 + bx + c = 0 \). - The nature of the roots depends on the discriminant \( D = b^2 - 4ac \). - If \( D < 0 \), the quadratic does not intersect the x-axis at all, regardless of whether x is positive or negative. - Therefore, this statement is **false** because the intersection depends on the discriminant, not the values of x being positive. ### Step 2: Analyze Statement (ii) **Statement (ii):** If only negative values are taken, the quadratic graph does not intersect the x-axis. - Similar to the first statement, the intersection of the graph with the x-axis depends on the discriminant \( D \). - If \( D < 0 \), the quadratic does not intersect the x-axis, but this is not dependent on whether x is negative or positive. - Hence, this statement can also be **false** in certain cases, but it is not universally false as the first statement. ### Step 3: Analyze Statement (iii) **Statement (iii):** The intercept of the x-axis can be known when we substitute \( x = 0 \) in the quadratic function. - The x-intercepts are found by setting \( y = 0 \) in the equation \( y = ax^2 + bx + c \). - Substituting \( x = 0 \) gives \( y = c \), which provides the y-intercept, not the x-intercept. - Therefore, this statement is **false**. ### Step 4: Analyze Statement (iv) **Statement (iv):** There can be a minimum of zero and a maximum of two x-intercepts. - A quadratic can have: - 0 x-intercepts (when \( D < 0 \)), - 1 x-intercept (when \( D = 0 \), which means the graph touches the x-axis), - 2 x-intercepts (when \( D > 0 \)). - Thus, this statement is **true**. ### Conclusion Based on the analysis: - Statement (i) is false. - Statement (ii) can be false but is not universally false. - Statement (iii) is false. - Statement (iv) is true. Thus, the false statements are (i) and (iii). ### Final Answer The false statements are (i) and (iii).
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