Simon says "five time my age 4 years ago is the same as three time my age in 2 years" how old is simon
1 answer:
Simon is 13 years old
Let x be Simon's age
Thus 4 years ago his age was (x - 4) and 2 years from now his age is (x + 2)
Hence 5(x - 4) = 3(x + 2)
distributing both sides gives
5x-20 = 3x + 6
subtract 3x from both sides of the equation
5x - 3x - 20 = 6
2x - 20 = 6
add 20 to both sides
2x = 6 + 20 = 26
divide both sides by 2
x = = 13
Simon is 13 years old
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Answer:
(B)
General Formulas and Concepts:
<u>Calculus</u>
Limits
Derivatives
- The definition of a derivative is the slope of the tangent line.
Derivative Notation
Instantaneous Rates
- Tangent Line:
Step-by-step explanation:
Since we are trying to find a <em>rate</em> at which W(t) changes, we must find the <em>derivative</em> at <em>t</em> = 3.
We are given 2 close answer choices that would have the same <em>numerical</em> answer but different <em>meanings</em>:
- (A)
- (B)
If we look at answer choice (A), we see that our units would simply just be volume. It would not have the units of a rate of change. Yes, it may be the closest numerically correct answer, but it does not tell us the <em>rate</em> at which the volume would be changing and it is not a derivative.
If we look at answer choice (B), we see that our units would be cm³/s, and that is most certainly a rate of change. Answer choice (B) is also a <em>derivative</em> at <em>t</em> = 3, and a derivative tells us what <em>rate</em> something is changing.
∴ Answer choice (B) will give us the best estimate for the value of the instantaneous rate of change of W(t) when <em>t</em> = 3.
Topic: AP Calculus AB/BC (Calculus I/I + II)
Unit: Differentiation
Book: College Calculus 10e