Write the product as a sum.
9cos(6x) cos(9x)

9/2 [ cos(15x) + cos(3x) ]

Step-by-step explanation:

9cos(6x) . cos(9x) can be expressed as

= 9/2 * 2cos (6x) * cos(9x)  next  here we will apply the rule

2cosA . cosB = cos(A+B)  + cos( A-B)

where A = 6x , B = 9x

hence : 9cos(6x) . cos(9x)  expressed as a sum will be

= 9/2 * [cos( 6x+ 9x) + cos( 6x - 9x ) ]

= 9/2 [ cos (15x ) + cos(-3x) ]

the final sum = 9/2 [ cos(15x) + cos(3x) ]

answer

see attachment

explanation

the given function is

this function has y-intercept at

-4 and a slope of 2.

note that, the graph has a positive slope.

the graph that represents this function is the straight line that moves upward from left to right.

the graph touches the y-axis at -4.

the correct choice is the graph shown in the attachment.

the first one

step-by-step explanation:

just id the test.