Using the identity cos(2x) = 2 cos^2x - 1
18 + 9(2 cos^2 x - 1) = 27 cos x
18cos^2 x - 27 cos x + 9 = 0
2 cos^ x - 3 cos x + 1 = 0
(2 cos x - 1 )(cos x - 1 ) = 0
cos x = 1/2 , 1
x = pi/3, 5pi/3, 0, 2pi answer
Answer:
The vertex and the axis of symmetry in the attached figure
Step-by-step explanation:
we know that
The equation of a vertical parabola written in vertex form is equal to

where
a is the leading coefficient
(h,k) is the vertex of the parabola
and the equation of the axis of symmetry is equal to the x-coordinate of the vertex

In this problem
we have

This is a vertical parabola written in vertex form open upward
The vertex is a minimum
where
the vertex is the point (5,-7)
the x-coordinate of the vertex is 5
so
the equation of the axis of symmetry is equal to

The graph in the attached figure
Answer:
( - 2 - 5m ) / 3
Step-by-step explanation:
15m + 9n = - 6
9n = - 6 - 15m
Divide by 3 on both sides,
9n / 3 = - 6 / 3 - 15m / 3
3n = - 2 - 5m
n = ( - 2 - 5m ) / 3