In logarithm, inverse operations are applied.
A quadrilateral, has 4 sides and its internal angles sum, add up to 360, now... you have 3 angles give.. .but we don't have C
so.. C is the difference of all the three angles from 360 or

whatever that is, now, you'll get some value in x-terms
so.... now once we know what C is
you can if you want, do a search in google for "inscribed quadrilateral conjecture", I can do a quick proof if you need one
but in short, for a quadrilateral inscribed in a circle, each pair of opposites angles are "supplementary angles", namely they add up to 180°
so.. what the dickens does all that mean? well D+B=180 and A+C = 180
now. we know what A is, 2x+1
and by now, you'd know what C is from 360-x-2x-1-148
so... add them together then and

solve for "x"
<h3>
Answer: Yes they are equivalent</h3>
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Work Shown:
Expand out the first expression to get
(a-3)(2a^2 + 3a + 3)
a(2a^2 + 3a + 3) - 3(2a^2 + 3a + 3)
2a^3 + 3a^2 + 3a - 6a^2 - 9a - 9
2a^3 + (3a^2-6a^2) + (3a-9a) - 9
2a^3 - 3a^2 - 6a - 9
Divide every term by 2 so we can pull out a 2 through the distributive property
2a^3 - 3a^2 - 6a - 9 = 2(a^3 - 1.5a^2 - 3a - 4.5)
This shows that (a-3)(2a^2 + 3a + 3) is equivalent to 2(a^3 - 1.5a^2 - 3a - 4.5)