how to make an equation of (1,5)

Answer 1

to make an equation you need additional information, either the slope of the line or another point on the line, for a linear equation. Easiest is either y=5 or x=1, a horizontal or vertical line

You could make a quadratic equation, using the point as the vertex then

y=(x-1)^2 + 5 would be the most standard simplest equation through the point.

or

y=-(x-1)^2 +5, with the same vertex

But there are endless other equations, cubic or higher degree, or more complicated quadratics.