Question

Find the values of the $x+y$ and $x-y$ from the examples given below without solving for x and y

$4x+3y=24;3x+4y=25$

• A. $7$ , $-1$
• B. $1$ , $-7$
• C. $1$ , $7$
• D. $-7$ , $-1$

Answer 1

Answer: (A)

$7$ , $-1$

$\text{The given equations are}$

$4x+3y=24$ ...(i)
$3x+4y=25$ ...(ii)

On adding (i) and (ii), we get

$7x+7y=49\Rightarrow x+y=7$

On subtracting (ii) from (i), we get

$x-y=-1$

$\therefore x+y=7andx-y=-1$