It is good equation. Look, that:
81 = 3 x 3 x 3 x 3 = 3^4.
So you have to solve:
3^x = 3^4
exponents have to be the same, so
x=4
That's mean that A(4) = 81
The rule is x+2, y-3 so you apply it to each of these coordinates. Right 2, down 3.
A(-2,2) -> A'(0,-1)
B(-2,4) -> B'(0, 1)
D(2,2) -> D'(4,-1)
y = Acos(Bx) + D;
D = 4, A = 2. Now T = 2π/B = 5π/8, B = 2π/(5π/8) = 16/5
WE get y = 2cos(16/5x) + 4
Subtract -6 on both sides
Now you have x/-2 on the left and 3 on the right
Then multiply -2 on both sides, leaving you with x on the left and -6 on the right
So x< -6
