Question

Find x, if 3x − 5(y + x ) ^2 = 16 and 4x + 2(y + x )^ 2 = 30

Answer 1

x = 7

Explanation:

Start by solving for
`(y+x)^2` which is a common expression for both equations. Then in the first equation:

`3\,x5\,(y+x)^2=16\\3x-16=5\,(y+x)^2\\(y+x)^2=(3\,x-16)/(5)`

and in the second equation:

`4\,x+2\,(y+x)^2=30\\2\,(y+x)^2=30-4\,x\\(y+x)^2=15-2\,x`

Now we make the two
`(y+x)^2` expressions equal so we get:

`(3\,x-16)/(5) =15-2\,x\\3\,x-16=75-10\,x\\13\,x=75+16\\13\,x=91\\x=7`