Answer:
The matrix equation is ![\left[\begin{array}{ccc}1&1&1\\1&-1/2&0\\0&2&-1\end{array}\right]=\left[\begin{array}{c}120&35&20\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%261%261%5C%5C1%26-1%2F2%260%5C%5C0%262%26-1%5Cend%7Barray%7D%5Cright%5D%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D120%2635%2620%5Cend%7Barray%7D%5Cright%5D)
Step-by-step explanation:
* Lets change the story problem to equations
- The distance between the starting point and checkpoint 1 is x
- The distance between checkpoint 1 to checkpoint 2 is y
- The distance between checkpoint and the finish line is z
- The total distance for the race is 120 miles
∴ x + y + z = 120 ⇒ (1)
-The distance from the starting point to checkpoint 1 is 35 miles
more than half the distance from checkpoint 1 to checkpoint 2
∵ The distance from the starting point to checkpoint 1 is x
∵ The distance from checkpoint 1 to checkpoint 2 is y
- x is more than half y by 35
∴ x = 35 + (1/2) y ⇒ subtract (1/2) y from both sides
∴ x - (1/2) y = 35 ⇒ (2)
- The distance from checkpoint 2 to the finish line is 20 miles less
than twice the distance from checkpoint 1 to checkpoint 2
∵ The distance from checkpoint 2 to the finish line is z
∵ the distance from checkpoint 1 to checkpoint 2 is y
- z is less than twice y by 20
∴ z = 2y - 20 ⇒ add 20 to both sides
∴ z + 20 = 2y ⇒ subtract z from both sides
∴ 2y - z = 20 ⇒ (3)
* Now lets write the three equations
# x + y + z = 120 ⇒ (1)
# x - (1/2) y = 35 ⇒ (2)
# 2y - z = 20 ⇒ (3)
- Now lets write the matrix equation that models this situation
∴
