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MathQuiz 4.2
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Exponentials - Quiz 2   Last unanswered question  Question  Next unanswered question

Question 1 lion

Which of the following is the value of  e32   correct to 3 decimal places?
a) 0.405 .   b) 4.077 .
c) 4.482 .   d) 10.043 .

 

Not correct. Choice (a) is false.
Try again, this is  3 ln 2 .
Not correct. Choice (b) is false.
Try again, this is  3 2e.
Your answer is correct.
Not correct. Choice (d) is false.
Try again, this is  e3. 2
Question 2 lion

Which of the following is the value of  e-1.5   correct to 3 decimal places?
a) -4.482 .
b) 0.223 .
c) 0.552 .
d) None of the above,  ex   is not defined for negative numbers.

 

Not correct. Choice (a) is false.
Try again, this is  - e1.5.   Remember  ex   is positive for all values of  x.
Your answer is correct.
e-1.5 =-11.5 = 0.223. e
Not correct. Choice (c) is false.
Try again, this is  1.5e- 1.
Not correct. Choice (d) is false.
Try again, there is a correct answer. The natural logarithm is not defined for negative numbers but the exponential function is.
Question 3 lion

Which of the following is the value of  3e2 + 5   correct to 3 decimal places?
a) 37.167 .   b) 7.079 .
c) 27.167 .   d) 3289.899 .

 

Not correct. Choice (a) is false.
Try again, only the  e2   is multiplied by 3 .
Not correct. Choice (b) is false.
Try again, you have found  3ln2 +4 .
Your answer is correct.
3e2 +5 = 3× 7.3891+ 5 = 27.167.
Not correct. Choice (d) is false.
Try again, you have calculated  3e2+5 .
Question 4 lion

Which of the following solves  e2x = 15   for x correct to 3 decimal places?
a) x = 1.354 .   b) x = 2.015 .
c) x = - 1.354.   d) x = 2.759.

 

Your answer is correct.
To solve this equation we take the natural log of both sides and
2x = ln 15 ⇒ x = ln125= 1.3540.
Hence  x = 1.354   correct to 3 decimal places.
Not correct. Choice (b) is false.
Try again, when solving find  ln15   then divide by 2 .
Not correct. Choice (c) is false.
Try again, you seem to have gained a negative sign.
Not correct. Choice (d) is false.
Try again, you must take the natural log of both sides to solve this, not divide by  e.
Question 5 lion

Which of the following solves  x+2 e = 8   for x correct to 3 decimal places?
a) x = 1.792 .   b) x = 0.079 .
c) x = 0.943 .   d) x = 4.079.

 

Not correct. Choice (a) is false.
Try again, you must take the 2 away from  ln8,   not from 8 .
Your answer is correct.
To solve this equation we take the natural log of both sides and get
x + 2 =ln8
x =ln8- 2
x =0.0794 .
Hence  x = 0.079   correct to 3 decimal places.
Not correct. Choice (c) is false.
Try again, you must take the natural log of both sides before rearranging the equation, do not divide by  e. .
Not correct. Choice (d) is false.
Try again, check your signs when solving the equation.