8. A home security system has a pad with 9 digits (1 to 9). Find the number of possible 5-digit pass codes:
1 answer:
Answer:
a. 59049
b. 15120
Step-by-step explanation:
<u>a. If digits can be repeated:</u>
- There are 9 possible numbers for each digit
That is: possible 5-digit pass codes are 9×9×9×9×9==59049
<u>b. If digits cannot be repeated.</u>
There is
- 9 possibility for the first digit,
- 8 possibility for the second digit
- 7 possibility for the third digit
- 6 possibility for the fourth digit
- 5 possibility for the fifth digit
That is: possible 5-digit pass codes are 9×8×7×6×5=15120
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Answer:
(a) center: (0, 0); radius: 4
(b) center: (8, -3); radius: 10
(c) center: (-2, -7); radius: 7
(d) center: (6, 0); radius: 1
(e) center: (0, 0); radius: 5
(f) center: (3, 8); radius: 8
Step-by-step explanation:
In the figure attached, the complete question is shown.
Equation of a circle with center (h, k) and radius r:
(x - h)² + (y - k)² = r²
