diameter is 11.14
solve for d:
the slope-intercept form:
m - slope
b - y-intercept
we have the slope m = -3 and the y-intercept b = 1. substitute:
it is a linear function. we need only two points to plot the graph.
select two values of x. put them in the line equation and calculate the values of y.
for x = 0:
for x = 1:
notice, that'd be the standard form for a quadratic equation, all variables on the left-hand-side, sorted in ascending order.