Easy Maths Question (Quadratic Equations)?

If I understand this right, you have a system of equations:

√(x² + y²) = 300
x - (30 * 2) = y

If that's correct, we can solve this with substitution. First, I'll simplify the second equation:

x - 60 = y
x = y + 60

Now I'll square the first equation to get rid of the radical, then substitute the above expression for "x" to solve for "y":

x² + y² = 90000
(y + 60)² + y² = 90000
y² + 120y + 3600 + y² = 90000
2y² + 120y = 86400

I'll divide both sides by 2, then complete the square:

y² + 60y = 43200
y² + 60y + 900 = 44100
(y + 30)² = 44100
y + 30 = ±210
y = -30 ± 210
y = -240 and 180

Now that we have two y's we can solve for two x's:

x = y + 60
x = -240 + 60 and x = 180 + 60
x = -180 and 240

The solution to your two equations are:

(-180, -240) and (240, 180)

But since we cannot read the context of the problem, I don't know if the negative answer should be removed or not. That will have to be for you to determine.