Explanation:
a.
1) if A(2;9) and B(6;17), then it is possible to make up the equation of the required line according
2) the rule:
![(x-X_A)/(X_B-X_A) =(y-Y_A)/(Y_B-Y_A);](https://img.qammunity.org/2022/formulas/mathematics/college/sjmnyw8qdv5k9cyg4l7etjlzwx2ghkcbb2.png)
3) if to substitute the coordinates of A&B into the rule, then:
![(x-2)/(6-2)=(y-9)/(17-9); \ => \ (x-2)/(4)=(y-9)/(8); \ => \ (x-2)/(1)=(y-9)/(2);](https://img.qammunity.org/2022/formulas/mathematics/high-school/8eb56ydlrfss4do505yi1bjoy1wrndqfch.png)
or 2x-y+5=0 or y=2x+5 (slope-interception form).
P.S. note, the suggested solution is not the shortest one. This task can be solved if to make up the system of two equations in slope-interception form.
b. see the attached picture (the required line is red colour);
c. f(4)=13. Short explanation: if to substitute the coordinate x=4 into the equation y=2x+5, then y=2*4+5=13;
d. the domain is (-∞;+∞), the range is (-∞;+∞).