Answer:
![\large\boxed{y=(1)/(2)x-2}\\\boxed{f(8)=2}\\\boxed{\text{positive}}](https://img.qammunity.org/2020/formulas/mathematics/college/m27gwjeg6orhj6c81d67jmgxn1f9h6smpk.png)
Explanation:
The slope-intercept form of an equation of a line:
![y=mx+b](https://img.qammunity.org/2020/formulas/mathematics/high-school/8nudzfk4b5l0arb9iixag2w8am6zn99zlr.png)
m - slope
b - y-intercept → (0, b)
The fromula of a slope:
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/fc06wy5n2hf2a0hmyba6df4ibmxk1cn53a.png)
From the graph we hate x-intercept (4, 0) and y-intercept (0, -2) → b = -2
Calculate the slope:
![m=(-2-0)/(0-4)=(-2)/(-4)=(1)/(2)](https://img.qammunity.org/2020/formulas/mathematics/college/vudn9gs08rhtexxro0apodc2nc915or93h.png)
Put the value of te slope and the value of the y-intercept to the equation of a line:
![y=(1)/(2)x+(-2)=(1)/(2)x-2](https://img.qammunity.org/2020/formulas/mathematics/college/udbifck3ohhhrm649keohvnvkn24sz9qy6.png)
Determine f(8).
Put x = 8 to the equation of a line:
![f(8)=(1)/(2)(8)-2=4-2=2](https://img.qammunity.org/2020/formulas/mathematics/college/457aevw7e88835ldsf1pb3kbabm8yvmevj.png)
If there is a horizontal shift of 10 to the left, then we have a new line:
![g(x)=f(x+10)](https://img.qammunity.org/2020/formulas/mathematics/college/422f6ftrkh1hundmtfosgdnk5j0c99w1fu.png)
use the distributive property
![g(x)=(1)/(2)x+\left((1)/(2)\right)(10)-2=(1)/(2)x+5-2=(1)/(2)x+3](https://img.qammunity.org/2020/formulas/mathematics/college/3kds59dy9v0d9uu5sw9gdfzocbcbbrxh1a.png)
Calculate g(8):
![g(8)=(1)/(2)(8)+3=4+3=7>0](https://img.qammunity.org/2020/formulas/mathematics/college/b8u27mv5n217kbsui4qqqu6zjqofmpd8ge.png)