C.21
5^2-4=21
Explanation
0-9 = 10 numbers
1st digit can be 1 0f 10
2nd digit can be 1 of 9
3rd digit can be 1 of 8
4th digit can be 1 of 7
10 * 9 *8*7 = 5040 different combinations
Answer:
p1 = 5/3, p2 = 4
Step-by-step explanation:
Used Photo math app.
A is correct because the linear function is f(x) = x so it is a straight line through the origin with a slope of 1.
B is incorrect because it has a slope of 1 not 0
C is incorrect because it a straight diagonal line not a curvy one
D is incorrect because if you visualize the graph it goes through quadrant I and III not II and IV
The answer x = 7 is false here is why.

This further simplifies to solution,

Hope this helps.
r3t40