Question

Is (1,-4) a solution to the equation y=-2x

Answer 1

y = -2x

Your question lies in notation: (1,2) means x=1, y=2. It goes in the format (x,y).
So (1, -4) means x = 1, y = -4.

And to test whether the point satisfies the equation, you plug in x:

y = -2x = -2 * 1 = -2

And then you check:
Does -2 (the y-value you just solved for) equal -4 (the y-value they were asking)?

Since , the answer is no, (1, -4) is not a solution to the equation.