I think the second one is correct
Using logarithmic laws: log(a) + log(b) = log(ab)
log₄ (x + 9) + log₄ (x + 21) = log₄ [(x + 9)(x + 21)] = 3
Since we want the equation in terms of x, the next intuitive step is take 4 to the power of both sides, because the left hand side will simplify easily.



Solving the quadratic we get:



BUT, for the logarithmic equation to be defined, x > -9, so x≠ -25
Thus, the only solution is x = -5.
Complementary angles are those angles whose sum is 90 degree.
The measurement of two complementary angles are

There sum have to be 90 degree. That is

Combining like terms ,

Moving 20 to right side

Dividing both sides by 5

So the measurement of the angles are

So f(0) is 6. We see that in the points. When you look at the x value for the function on the left, you see the point (0,6) when x is 0 y is always 6.