Example

Finding the Intercepts of y=x22x8y = x^2 - 2x - 8

To find the intercepts of the parabola described by the equation y=x22x8y = x^2 - 2x - 8, determine where the graph crosses each axis.

Calculating the y-intercept: Substitute x=0x = 0 into the equation and solve for yy:

y=022(0)8y = 0^2 - 2(0) - 8 y=8y = -8

This gives the y-intercept at the point (0,8)(0, -8).

Calculating the x-intercepts: Substitute y=0y = 0 into the equation and solve the resulting quadratic equation for xx:

0=x22x80 = x^2 - 2x - 8

Solve by factoring the right side of the equation:

0=(x4)(x+2)0 = (x - 4)(x + 2)

Apply the Zero Product Property by setting each factor equal to zero:

x4=0extorx+2=0x - 4 = 0 \quad ext{or} \quad x + 2 = 0

x=4extorx=2x = 4 \quad ext{or} \quad x = -2

This yields the x-intercepts at the points (4,0)(4, 0) and (2,0)(-2, 0).

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Updated 2026-05-15

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