Answer:
The function rule is:
![y = -3x-5](https://img.qammunity.org/2021/formulas/mathematics/high-school/gjzscjtp73ewk019f0rylff3na30kiykrq.png)
Explanation:
Using the given input/output values, we can take two pairs of input-output values for finding the rule.
The function is a linear function as the input and output are changing linearly.
Required pairs are:
(1,-8) and (2, -11)
The general rule for linear function is:
![y = mx+b](https://img.qammunity.org/2021/formulas/mathematics/high-school/65dxh1fg3jfjanwatlvuvqa4t096a6as1k.png)
m is the slope of the function calculated using the formula
![m = (y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2021/formulas/mathematics/high-school/qpav2tpezfjoebw1smt5zxyas28f0tlb4m.png)
Putting the values
![m = (-11+8)/(2-1)\\m = (-3)/(1)\\m = -3](https://img.qammunity.org/2021/formulas/mathematics/high-school/f7gotstur81p3h9hfrvunkiuvtu2vb5jnf.png)
Putting in equation
![y = -3x+b](https://img.qammunity.org/2021/formulas/mathematics/college/rt566i0cilfqb9g4d88qnfy588kek20n28.png)
To find the value of b, putting (1,-8) in the equation
![-8 = -3(1) +b\\-8 = -3+b\\-8+3 = b\\b = -5](https://img.qammunity.org/2021/formulas/mathematics/high-school/way4xqc7amrjss2lp6bxjjxtlcgjhc6pas.png)
Putting the values
![y = -3x-5](https://img.qammunity.org/2021/formulas/mathematics/high-school/gjzscjtp73ewk019f0rylff3na30kiykrq.png)
Hence,
The function rule is:
![y = -3x-5](https://img.qammunity.org/2021/formulas/mathematics/high-school/gjzscjtp73ewk019f0rylff3na30kiykrq.png)