Answer: (a) x = -1
Step-by-step explanation:
<u>Given</u>
x - 8 = - 9
<u>Add 8 on both sides to isolate x</u>
x - 8 + 8 = - 9 + 8

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I believe the answer is b and e
In order to confirm which of the given above is an identity, what we are going to do is to check them each. By definition, an identity<span> is an equality relation A = B.
After checking each options, the answers that are considered as identities would be options C and D. So here is how we proved it. Let's take option C.
</span><span>cos^2(3x)-sin^2(3x)=cos(6x)
cos^2(3x)-sin^2(3x)=cos(2*3x)
cos^2(3x)-sin^2(3x)=cos(3x+3x)
cos^2(3x)-sin^2(3x)=cos(3x)cos(3x)-sin(3x)sin(3x)
cos^2(3x)-sin^2(3x)=cos^2(3x)-sin^2(3x)
</span>So based on this, we can conclude that <span>cos^2 3x-sin^2 3x=cos6x is an identity.
This is also the same process with option D.
Hope this answer helps.</span>
Answer:
x=8
Step-by-step explanation: