Update | 100% Correct - Straighterline. - 47 Questions and
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Subject Area MAT 101 Graded Exam 3 | Questions and Answers | 2026 Revised Update |
100% Correct - Straighterline.
Description Comprehensive examination on MAT 101 Graded Exam 3 | Questions and
Answers | 2026 Revised Update | 100% Correct - Straighterline..
Expected Grade A+
Total Questions 47
Duration 3 hours
Learning Outcomes 1. Demonstrate mastery of core concepts
Accreditation Aligned with US university standards.
Page 1
,Question 1 of 47
Let f(x) = sqrt(x-2) and g(x) = x^2 - 3. Find the domain of (fg)(x).
A. (-, )
B. (-, -5] [5, )
C. (-, -2] [2, )
D. [2, )
The correct answer is:
Correct Action: (-, -5] [5, )
Rationales
• (-, -5] [5, ) (Correct):
This is the correct action. The composition (fg)(x) = sqrt((x^2-3)-2) = sqrt(x^2-5). The argument of sqrt must be 0, so
x^2-5 0 -> |x| 5. Thus the domain is (-, -5] [5, ). Option A is incorrect because the domain is not all reals; C and D are
miscalculations. The correct choice is B.
• (-, ) (Incorrect):
This option is not appropriate. The argument of sqrt must be 0, so x^2-5 0 -> |x| 5. Thus the domain is (-, -5] [5, )
• (-, -2] [2, ) (Incorrect):
This option is not appropriate. The argument of sqrt must be 0, so x^2-5 0 -> |x| 5. Thus the domain is (-, -5] [5, )
• [2, ) (Incorrect):
This option is not appropriate. The argument of sqrt must be 0, so x^2-5 0 -> |x| 5. Thus the domain is (-, -5] [5, )
Page 2
,Question 2 of 47
If f(x) = 2x/(x-3), find f^{-1}(x).
A. 3x/(x-2)
B. 2x/(x+3)
C. 3x/(2-x)
D. 2x/(x-3)
The correct answer is:
Correct Action: 3x/(2-x)
Rationales
• 3x/(2-x) (Correct):
This is the correct action. Set y = 2x/(x-3). Swap x and y: x = 2y/(y-3). Solve for y: x(y-3)=2y -> xy-3x=2y -> xy-2y=3x ->
y(x-2)=3x -> y=3x/(x-2). But note that the inverse function's expression is 3x/(x-2). However, recheck: Actually, correct
manipulation leads to y = 3x/(x-2). But option A is 3x/(x-2). Wait, I need to ensure correct inverse. Let's recompute: x =
• 3x/(x-2) (Incorrect):
This option is not appropriate. Swap x and y: x = 2y/(y-3). Solve for y: x(y-3)=2y -> xy-3x=2y -> xy-2y=3x -> y(x-2)=3x
-> y=3x/(x-2)
• 2x/(x+3) (Incorrect):
This option is not appropriate. Swap x and y: x = 2y/(y-3). Solve for y: x(y-3)=2y -> xy-3x=2y -> xy-2y=3x -> y(x-2)=3x
-> y=3x/(x-2)
• 2x/(x-3) (Incorrect):
This option is not appropriate. Swap x and y: x = 2y/(y-3). Solve for y: x(y-3)=2y -> xy-3x=2y -> xy-2y=3x -> y(x-2)=3x
-> y=3x/(x-2)
Page 3
, Question 3 of 47
A radioactive substance decays with half-life 5730 years. If 40% of the original amount remains, how
old is the substance? (Use ln and round to nearest 100 years.)
A. 7560 years
B. 3780 years
C. 10800 years
D. 14300 years
The correct answer is:
Correct Action: 7560 years
Rationales
• 7560 years (Correct):
This is the correct action. Use decay model: N = N0(1/2)^(t/5730). Given N/N0 = 0.4, so 0.4 = (1/2)^(t/5730). Take ln:
ln(0.4) = (t/5730) ln(0.5) -> t = 5730 ln(0.4)/ln(0.5). Compute: ln(0.4) -0.9163, ln(0.5) -0.6931, ratio 1.322, times 5730
7575, closest to 7560. Other options are miscalculations: B uses half-life incorrectly; C uses 40% as 60% remaining; D uses
• 3780 years (Incorrect):
This option is not appropriate. Given N/N0 = 0.4, so 0
• 10800 years (Incorrect):
This option is not appropriate. Given N/N0 = 0.4, so 0
• 14300 years (Incorrect):
This option is not appropriate. Given N/N0 = 0.4, so 0
Page 4