Video: Zeros of Quadratic Functions

Given that 𝑓(π‘₯) is a quadratic function and π‘₯ = 4 is a root of the equation 𝑓(π‘₯) = 0, what is the value of 𝑓(4)?

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Video Transcript

Given that 𝑓 of π‘₯ is a quadratic function and π‘₯ equals four is a root of the equation 𝑓 of π‘₯ equals zero, what is the value of 𝑓 of four?

We’re told that π‘₯ equals four is a root of the equation. Roots of a function are the π‘₯ intercepts. And the 𝑦-coordinate of points lying on the π‘₯-axis is zero. So the place of the roots are where 𝑓 of π‘₯ equals zero.

The function of π‘₯ equal to zero, 𝑓 of four in this case, is equal to zero. Because π‘₯ equals four is a root of this equation, if we plug in four for π‘₯, the outcome is going to be zero. The function of four equals zero.

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