# matrices help?

For what value of c does the linear system with augmented matrix

1 0 0 1

0 1 c 2

0 0 1 3

have the unique solution x1=1, x2=-7,x3=3?

### 2 Answers

Relevance

- AlanLv 74 weeks agoBest Answer
1 0 0 1

0 1 c 2

0 0 1 3

Use echelon row reduction to find the solution

subtract (c) times row 3 from row 2

1 0 0 1

0 1 0 (2-3c)

0 0 1 3

so you now know

x_1 =1

x_2 = (2-3c )

x_3 = 3

so two items contain no c value and already correct.

x_2 = 2-3c

x_2= -7

2 -3c = -7

-3c = -9

c = -9/-3 = 3

answer

c = 3

Still have questions? Get your answers by asking now.