Which of the following uses the properties of exponents to correctly rewrite f(x)=2⋅(513x+4)3−7

in the form f(x)=a(b)x−h+k
and to determine the value of h?(1 point)
Responses

h=−4
h equals negative 4

h=12
h equals 12

h=−12
h equals negative 12

h=7

1 answer

To rewrite the function \( f(x) = 2 \cdot (5^{13x + 4})^3 - 7 \) in the form \( f(x) = a(b)^x - h + k \), we first simplify \( f(x) \).

We start by simplifying \( (5^{13x + 4})^3 \) using the property of exponents:

\[ (5^{13x + 4})^3 = 5^{3(13x + 4)} = 5^{39x + 12} \]

So, we can rewrite \( f(x) \) as:

\[ f(x) = 2 \cdot 5^{39x + 12} - 7 \]

Now, we want to express this in the form \( f(x) = a(b)^x - h + k \).

We can identify:

  • \( a = 2 \)
  • \( b = 5^{39} \) (since \( b^x \) would be \( 5^{39x} \), where \( b \) is effectively \( 5^{39} \))
  • The term \( -h + k \) would then come from \( -7 \).

To express the function in the required form, we note the \( h \) term is related to the constant modifications:

  1. The function becomes: \[ f(x) = 2 \cdot 5^{39x} \cdot 5^{12} - 7 \] Simplifying further, \[ f(x) = 2 \cdot 5^{39x} \cdot (5^{12}) - 7 \]

    Recognizing \( k = 2 \cdot 5^{12} \) and noting we need it in the form \( -h + k \), we can express the \( -7 \) as \( -h + 0 \):

    • Therefore, it implies \( -h = -7 \), giving \( h = 7 \).

Thus, the value of \( h \) is:

h = 7.