For what value of a does (one-seventh) superscript 3 a + 3 baseline = 343 superscript a minus 1?
–1
0
1
no solution

  a = 0

Step-by-step explanation:

I find a graphing calculator useful for such questions. It shows the solution to be a = 0. For the graph, we have rewritten the equation from

  (1/7)^(3a+3) = 343^(a-1)

to

  (1/7)^(3x+3) -343^(x-1) = 0 . . . . . this graphing calculator likes x for the independent variable

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If you recognize that 343 is the cube of 7, you might solve this by taking logarithms to the base 7.

 (7^-1)^(3a+3) = (7^3)^(a-1)

Equating exponents of 7*, we get ...

  -(3a+3) = 3(a -1)

  -3a -3 = 3a -3 . . . . . eliminate parentheses

  0 = 6a . . . . . . . . . . . add 3+3a

  0 = a . . . . . . . . . . . . divide by 6

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* Equating exponents of 7 is the same as taking logarithms to the base 7. Here, we use the rules of exponents ...

  1/a^b = a^-b

  (a^b)^c = a^(bc)

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a

step-by-step explanation: