Question

A parabola has equation y = 4x² + x + c. One x-intercept is -3. What is the value of c?

A parabola has equation $$\displaystyle{y}={4}{x}²+{x}+{c}$$. One x-intercept is -3. What is the value of c?

The x-intercept corresponds to the point (-3,0). Substitute this point to the equation and solve for c: $$\displaystyle{0}^{{2}}={4}{\left(-{3}\right)}^{{2}}+{\left(-{3}\right)}+{c}$$