contestada

For what value of a does (one-ninth) Superscript a + 1 Baseline = 81 Superscript a + 1 Baseline times 27 Superscript 2 minus a?

Respuesta :

Answer:

[tex]a = -4[/tex]

Step-by-step explanation:

The equation to solve for "a" is:

[tex](\frac{1}{9})^{a+1}=81^{a+1}*27^{2-a}[/tex]

The first step is to convert all of them to same bases.

9, 81, and 27, all can be expressed in base 3, lets do this:

[tex](\frac{1}{9})^{a+1}=81^{a+1}*27^{2-a}\\(3^{-2})^{a+1}=(3^4)^{a+1}*(3^3)^{2-a}[/tex]

We can use the property: [tex](a^b)^c=a^{bc}[/tex] to simplify further:

[tex](3^{-2})^{a+1}=(3^4)^{a+1}*(3^3)^{2-a}\\3^{-2a-2}=3^{4a+4}*3^{6-3a}[/tex]

The right side has 2 same bases multiplied, we can simplify this using the property:  [tex]a^x * a^y = a^{x+y}[/tex]

Thus, we have:

[tex]3^{-2a-2}=3^{4a+4}*3^{6-3a}\\3^{-2a-2}=3^{4a+4+6-3a}}\\3^{-2a-2}=3^{a+10}[/tex]

Now, both sides have same base, so exponents would be equal. Now lets equate and solve for "a":

[tex]3^{-2a-2}=3^{a+10}\\-2a-2=a+10\\3a=-12\\a=-4[/tex]

So,

a = -4

Answer:

A) -4

Step-by-step explanation: