Big Ideas Math Algebra 2, 2014
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Big Ideas Math Algebra 2, 2014 View details
4. Adding and Subtracting Rational Expressions
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Exercise 53 Page 390

Use inspection. Use a calculator.

Function: g(x)=2.3058/x+12.2+0.003
Transformation: We should translate the graph of f 12.2 units to the left and 0.003 unit up.

Practice makes perfect
Let's analyze the given function.
g(x)=(97.6)(0.024)+x(0.003)/12.2+x
g(x)=0.003x+2.3424/x+12.2
We will use inspection to find how we should begin to rewrite the function g(x)= 0.003x+2.3424x+12.2 to obtain the form g(x)= ax-h+k. g(x)=0.003x+2.3424/x+12.2 Since the denominator of the given simple rational function is x+12.2, we want to rewrite its numerator in the form a( x+12.2)+ b for some a and b. Let's compare the appropriate expressions of numerators to each other. 0.003x+2.3424= a(x+12.2)+ b Since the coefficients in front of x must be equal, we know that a= 0.003. a(x+12.2)+ b ⇓ 0.03(x+12.2)+ b Next, the numerators, x, and 0.003(x+12.2)+ b, should be equal. Let's find b!
0.003x+2.3424= 0.003(x+12.2)+ b
â–Ľ
Solve for b
0.003x+2.3424=0.003x+0.003(12.2)+ b
0.003x+2.3424=0.003x+0.0366+ b
2.3424=0.0366+ b
2.3058= b
b=2.3058
Therefore, we should rewrite the numerator of the given function in the following way. 0.003x+2.3424= 0.003(x+12.2)+ b ⇓ 0.003x+2.3424= 0.003(x+12.2)+ 2.3058 Finally, let's rewrite the function g in the form g(x)= ax-h+k.
g(x)=0.003x+2.3424/x+12.2
â–Ľ
Rewrite
g(x)=0.003(x+12.2)+2.3058/x+12.2
g(x)=0.003(x+12.2)/x+12.2+2.3058/x+12.2
g(x)=0.003/1+2.3058/x+12.2
g(x)=0.003+2.3058/x+12.2
g(x)=2.3058/x+12.2+0.003
We are asked to describe the graph of g as a transformation of the graph of f(x)= ax. First, in our case a=2.3058. f(x)=2.3058/x Now we describe the transformation of graph f to obtain the graph of a rational function g.
Transformations of y=f(x)
Vertical Translations Translation up k units, k>0 y=f(x)+ k
Translation down k units, k>0 y=f(x)- k
Horizontal Translations Translation right h units, h>0 y=f(x- h)
Translation left h units, h>0 y=f(x+ h)

Notice the following. f(x)=2.3058/x, g(x)=2.3058/x+ 12.2+ 0.003 ⇓ g(x)=f(x+ 12.2)+ 0.03 Therefore, we should translate the graph of f 12.2 units to the left and 0.003 units up to get the graph of g.