Given :
An expression (cos 6m)(cos 2m) .
To Find :
We need to express it in terms as sum or difference.
Solution :
We know,
cos( A + B ) = cosA cos B - sin A sin B
cos( A - B ) = cosA cos B + sin A sin B
Adding both the equations we get :
2cos A cos B = cos( A + B) + cos( A - B )
or
cos A cos B = cos( A + B) + cos( A - B )/2
Putting value of A = 6m and B = 2m in above equation, we get :
(cos 6m)(cos 2m) = cos( 6m + 2m ) + cos( 6m - 2m )/2
(cos 6m)(cos 2m) = cos(8m) + cos(4m)/2
Hence, this is the required solution.
<span>Simplifying
(2x + -7y ) = 0
Multiply
(2x + -7y) * (x + y) </span><span>
(2x * (x + y) + -7y * (</span><span>x + y)) = 0
</span>((x * 2x + y * 2x) + -7y * (x + y)) = 0<span>
</span>Reorder the terms:
((2xy + 2x2) + -7y * (x + y)) = 0
((2xy + 2x2) + -7y * (x + y)) = 0
(2xy + 2x2 + (x * -7y + y * -7y)) = 0
(2xy + 2x2 + (-7xy + -7y2)) = 0<span>
Reorder the terms:
(2xy + -7xy + 2x2 + -7y2) = 0
</span>
<span>Combine like terms: 2xy + -7xy = -5xy
(-5xy + 2x2 + -7y2) = 0
</span>Solving -5xy + 2x2 + -7y2 = 0<span>
Solving for variable 'x'.
Factor a trinomial.
(2x + -7y)(x + y) = 0
</span>
Answer:1.A
2.D
Step-by-step explanation:
