Re: Given two equations: x2 9 0 and y2 16 > 0. Which of the followin
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11 Dec 2024, 10:24
We know $x2−9≤0&y2−16>0$; we need to check from the options that which of them is true.
The equation $x2−9≤0$ is same as $x2≤9⇒−3<x<3$ whereas the second equation $y2−16>0⇒y>4$ or $y<−4$
The minimum positive integral value of the product of $x$ and $y$ will come if we take either $x$ and $y$ both negative or both positive. The minimum possible negative values of $x$ and $y$ are -2 and -3 , so we get the product $xy=−2×−3=6&$ the minimum possible positive values of x and y are 1 and 5 respectively, so we get the product $xy=1×5=5$.
So, the minimum positive integral value of the product of x and y is 5 .
Similarly to find the maximum negative integral value of $x$ and $y$, we would consider exactly one of $x$ and $y$ negative and take their minimum possible values. If we take $x=−1$ and $y=5$, we get the product $xy=−1×5=−5&$ if we take $x=1$ and $y=−5$, we get $xy=1×−5=−5$
So, the maximum possible negative integral value of the product of x and y is -5 .
Hence options (B) \& (C) are correct.