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Exponentials - Quiz 3   Last unanswered question  Question  Next unanswered question

Question 1 lion

Which of the following is the value of  e3   correct to 3 decimal places?
a) 1.097 .   b) 20.086 .
c) 8.155 .   d) 7.389 .

 

Not correct. Choice (a) is false.
Try again, this is  ln 3.
Your answer is correct.
Not correct. Choice (c) is false.
Try again, this is  3e.
Not correct. Choice (d) is false.
Try again, this is  e2 .
Question 2 lion

Which of the following is the value of  e-3   correct to 3 decimal places?
a) -10.086 .   b) 0.552 .
c) 0.049 .   d) 0.050 .

 

Not correct. Choice (a) is false.
Try again, this is  - e3.   Remember  ex   is positive for all values of  x .
Not correct. Choice (b) is false.
Try again, this is  1.5e-1 .
Not correct. Choice (c) is false.
Try again, be careful how you round.
Your answer is correct.
e-3 = 1-= 0.04978 = 0.050. e3
Question 3 lion

Which of the following is the value of  5- 3e-2   correct to 3 decimal places?
a) 4.594 .   b) 31.670 .
c) 2.921 .   d) -17.167 .

 

Your answer is correct.
5 - 3e- 2 = 5- 3 × 0.1353 = 5 - 0.406 = 4.594   correct to 3 decimal places.
Not correct. Choice (b) is false.
Try again, you have calculated  5+ 3e2.
Not correct. Choice (c) is false.
Try again, you have found  5 - 3ln 2.
Not correct. Choice (d) is false.
Try again, you have calculated  5 - 3e2 .
Question 4 lion

Which of the following solves  e-3x = 18   for x correct to 3 decimal places?
a) x = 1.792 .   b) x = - 0.963.
c) x = - 1.792.   d) x = - 2.207.

 

Not correct. Choice (a) is false.
Try again, when solving find  ln18   then divide by -3 .
Your answer is correct.
To solve this equation we take the natural log of both sides and
- 3x = ln18 ⇒ x = - ln138= - 0.963.
Hence  x = 1.354   correct to 3 decimal places.
Not correct. Choice (c) is false.
Try again, when solving find  ln18   then divide by -3 .
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  e2x-1 = 16   for x correct to 3 decimal places?
a) x = 1.354 .   b) x = 0.943.
c) x = 0.886.   d) x = 1.886.

 

Not correct. Choice (a) is false.
Try again, you must add 1 to  ln16,   not from 16 .
Not correct. Choice (b) is false.
Try again, you must take the natural log of both sides before rearranging the equation, do not divide by  e. .
Your answer is correct.
To solve this equation we take the natural log of both sides and get
2x - 1 =ln 16
2x =ln 16- 1
x =0.8862 .
Hence  x = 0.886   correct to 3 decimal places.
Not correct. Choice (d) is false.
Try again, check your signs when solving the equation.