7t+2r-3t+r what is the answer
2 answers:
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If this exact question is repeatedly deleted, it's probably because of the ambiguity of the given equation. I see two likely interpretations, for instance:
or
If the first one is what you intended, then
and it follows that
2<em>k</em> + 8 = 3 ==> 2<em>k</em> = -5 ==> <em>k</em> = -5/2
If you meant the second one, then
which would give
<em>k</em> + 9 = 3 ==> <em>k</em> = -6
And for all I know, you might have meant some other alternative... When you can, you should include a picture of your problem.
Answer:
Step-by-step explanation:
We want to find
This can be rewritten as;
Recall that;
We evaluate now to obtain;
Note that f(x) as given is <em>not</em> invertible. By definition of inverse function,
which is a cubic polynomial in with three distinct roots, so we could have three possible inverses, each valid over a subset of the domain of f(x).
Choose one of these inverses by restricting the domain of f(x) accordingly. Since a polynomial is monotonic between its extrema, we can determine where f(x) has its critical/turning points, then split the real line at these points.
f'(x) = 3x² - 1 = 0 ⇒ x = ±1/√3
So, we have three subsets over which f(x) can be considered invertible.
• (-∞, -1/√3)
• (-1/√3, 1/√3)
• (1/√3, ∞)
By the inverse function theorem,
where f(a) = b.
Solve f(x) = 2 for x :
x³ - x + 2 = 2
x³ - x = 0
x (x² - 1) = 0
x (x - 1) (x + 1) = 0
x = 0 or x = 1 or x = -1
Then can be one of
• 1/f'(-1) = 1/2, if we restrict to (-∞, -1/√3);
• 1/f'(0) = -1, if we restrict to (-1/√3, 1/√3); or
• 1/f'(1) = 1/2, if we restrict to (1/√3, ∞)