Question

Which of the following has a graph that is a straight line?

Equation 1: y = 2x + 7
Equation 2: y2 = x − 1
Equation 3: y = 2x2 + 4
Equation 4: y = 3x3

Answer 1

A straight line has an equation

$y=mx+b.$

The only possible choice is A (m=2, b=7).

Note that equations 2 and 3  determine quadratic parabolas and equation 4 determines cubic parabola. All parabola (quadratic and cubic are not straight lines).