The simplified form is 6x-6
Use the Sum of Angles In a Triangle therom.
You HAVE to use Pemdas.
2[3(4^2+1)]-2^3
2(3(16+1))-2^3
2(3(17))-2^3
2*51-2^3
102-8
94.
Explanation: you use Pemdas P-parenthesis
E-exponents
M-multiplication
D-division
A-addition
S-subtraction
I believe the answer is 78.54 , D
From the recursive rule, you can tell the initial value is 3 and the common ratio is 12. The explicit rule is always
.. (n-th term) = (initial value)*(common ratio)^(n -1)
Subsituting the values you know, you have
.. an = 3*12^(n-1)