Big Ideas Math Algebra 2, 2014
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Big Ideas Math Algebra 2, 2014 View details
7. Transformations of Polynomial Functions
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Exercise 30 Page 210

Find a point on the graph of f.

Example Solution:

Practice makes perfect
We are asked to find a transformation that moves the graph of f(x)=x^5-3x^4+2x-4 to a graph with a y-intercept of - 2. We can do this by moving any point on the graph of f to the point (0,2). Let's calculate f(0) to find the y-intercept of the graph of f.
f(x)=x^5-3x^4+2x-4
f( 0)= 0^5-3( 0)^4+2( 0)-4
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Evaluate right-hand side
f(0)=0-0+0-4
f(0)=-4
A translation up by 2 units moves the point (0,-4) to (0,-2), so it moves the graph of f to a graph with a y-intercept at -2. Let's find the equation of the new graph. To represent a translation up by 2 units we need to add 2 to f(x).
g(x)=f(x)+2
g(x)= x^5-3x^4+2x-4+2
g(x)=x^5-3x^4+2x-2
The diagram below illustrates the two graphs and the transformation.

Alternative Solution

Alternative way of thinking

As mentioned in the solution, any point on the graph of f can be translated to the y-axis to become the y-intercept of the transformed graph. For example, if we translate the graph 2 units to the left and 14 units up, then the point (2,-16) of the graph of f becomes the y-intercept at - 2 of the transformed graph.