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Shifting the Input

Part of the Functions & Transformations section of Coddy's Algebra 2 journey. Lesson 3 of 55.

Here is f(x)=x2f\left(x\right) = {x}^{2}. Its lowest point is (0, 0). Now put x−3x-3 into f instead of x. This gives y=f(x−3)y = f\left(x-3\right). Does the curve move left or right? Most people say left, because of the minus sign.

The curve y = x squared, lowest at the origin

You can work it out. The curve of f is lowest when the input of f is 0. So find the x that makes x−3x-3 equal to 0. At that x the curve has its lowest point, called the vertex. The curve keeps the same shape.

challenge icon

Challenge

Draw y=f(x−3)y = f\left(x-3\right) for f(x)=x2f\left(x\right) = {x}^{2}. The light curve is f itself. Drag the vertex (the lowest point) first, then the second point.

Try it yourself

y=f(x−3)y = f\left(x-3\right)

Draw the parabola

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