Question

If 2x-y=4 then x+y=5,then the value of xy is

Answer 1

x+ y = 5    2x-y = 4   solve x and y





X = 3 and Y = 2.  Here is how we find this.

What we have to do is use the first equation to get a value for y.  This is quite easy because all we must do is say

x + y = 5 so y = 5 -x

Now we plug that value into the second equation.

2x - (5-x) = 4

This becomes

2x - 5 + x = 4 (because you are subtracting negative x, you are in effect adding x)

3x - 5 = 4

3x = 9

x = 3

If x = 3, then 3 + y = 5 and y = 2

Answer 2

answer is x=3 y=2 xy =6