Question

if x+y=15 a,nd x-y=4 then find the value of x2 -y2​

Answer 1

As per the data given in the question,

We have to determine the value of $x^2-y^2$ if $x+y=15 \:and\: x-y=4$

For finding the value of given expression,

We need to first determine the value of x and y by solving the equation $x+y=15 \:and\: x-y=4$

So, for solving the value of x and y,

We will add both the above equation,

We will get it as,

$x+y=15 ----(1)\\x-y=4 -----(2)\\Add\:(1) and \:(2)\\x+y+x-y=15+4\\=>2x = 19\\=>x=\frac{19}{2}\\From (1)\\\Since x+y=15\\As\; x = \frac{19}{2}= 9.5\\=>9.5+y=15\\=>y=15-9.5\\=>y=5.5$

So, value of the expression  $x^2-y^2$ will be,

$(9.5^2-5.5^) = (9.5+5.5)(9.5-5.5) = 15\times 4 = 60$

Answer 2

This the answer I hope it helps you