General Form of an Exponential Function Quick Check

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Question
Which of the following uses the properties of exponents to correctly rewrite the function f(x)=7⋅22x+3⋅2−(x+5)+3
in the form f(x)=a(b)x−h+k
?(1 point)
Responses

f(x)=7⋅2x+8+3
f left parenthesis x right parenthesis equals 7 times 2 superscript x plus 8 baseline plus 3

f(x)=7⋅23x+8+3
f left parenthesis x right parenthesis equals 7 times 2 superscript 3 x plus 8 baseline plus 3

f(x)=7⋅2x−2+3
f left parenthesis x right parenthesis equals 7 times 2 superscript x minus 2 baseline plus 3

f(x)=2x−2+10

1 answer

To rewrite the function \( f(x) = 7 \cdot 2^{2x + 3} \cdot 2^{-(x + 5)} + 3 \) in the form \( f(x) = a(b)^{x - h} + k \), we need to simplify the expression using the properties of exponents.

  1. Notice that \( 2^{2x + 3} \cdot 2^{-(x + 5)} \) can be combined using the property of exponents that states \( a^m \cdot a^n = a^{m+n} \): \[ 2^{2x + 3} \cdot 2^{-(x + 5)} = 2^{(2x + 3) - (x + 5)} = 2^{2x + 3 - x - 5} = 2^{x - 2} \]

  2. Substitute this back into the function: \[ f(x) = 7 \cdot 2^{x - 2} + 3 \]

Now we can identify the values for \(a\), \(b\), \(h\), and \(k\):

  • \( a = 7 \)
  • \( b = 2 \)
  • \( h = 2 \) (since it is \( x - 2 \))
  • \( k = 3 \)

So the function \( f(x) = 7 \cdot 2^{x - 2} + 3 \) is in the desired form.

From the provided options, the correct rewritten function is:

f(x)=7⋅2x−2+3

This corresponds to the third option from your list.