Given:
The slope of the line joining points (3,2) and (0,a) is -1.
To find:
The value of a.
Solution:
If a line passes through two points
and
, the slope of a line is:
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2022/formulas/mathematics/college/bpkoq3bvkesp0enrhm14yweiccwgnbhsww.png)
The slope of the line joining points (3,2) and (0,a) is -1. So,
![(a-2)/(0-3)=-1](https://img.qammunity.org/2022/formulas/mathematics/college/qysl0olyar4p269qe0x4361dtgb1t7qf8f.png)
![(a-2)/(-3)=-1](https://img.qammunity.org/2022/formulas/mathematics/college/rnjgjfns7dwfv8kxygwb00k1aso5eoctdd.png)
Multiply both sides by -3.
![a-2=-1(-3)](https://img.qammunity.org/2022/formulas/mathematics/college/kp2bnemnym88dn8kks0bjgcket9nrxv95c.png)
![a-2=3](https://img.qammunity.org/2022/formulas/mathematics/college/xo26t134i1i5wbxslff4g1pq16vzw4ng6o.png)
![a=3+2](https://img.qammunity.org/2022/formulas/mathematics/college/ymstbxlhqmiygrvhb7blg32l4qa30cgiyb.png)
![a=5](https://img.qammunity.org/2022/formulas/mathematics/high-school/enxljp3wakks3z5e6nymfynahbeot6pm23.png)
Therefore, the value of a is 5.