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If $x+y=19$ and $x-y=7$, then $xy=?$
Given: Linear equations: $x+y=19$ and $x-y=7$
To do: To find the value of $xy$.
Solution:
$\Rightarrow x+y=19$ ....... $( 1)$
$\Rightarrow x-y=7$ ....... $( 2)$
On adding $( 1)$ and $( 2)$, we get
$x+y+x-y=19+7$
$\Rightarrow 2x=26$
$\Rightarrow x=13$
On putting $x=13$ in equation $( 1)$, we get
$\Rightarrow 13+y=19$
$\Rightarrow y=6$
$\therefore xy=13\times6=78$
Updated on: 10-Oct-2022
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