Question

The solution of the system x + y – 3z = – 6, – 7y + 7z = 7, 3z = 9 is

Options

•  x = 1, y = 2, z = 3

• x = – 1, y = 2, z = 3

• x = – 1, y = – 2, z = 3

• x = 1, y = − 2, z = 3

Answer 1

x = 1, y = 2, z = 3

Explanation;

Hint:

x + y – 3x = – 6 ...(1)

– 7y + 7z = 7  ...(2)

3z = 9  ...(3)

From (3) we get

z = `9/3` = 3

Substitute the value of z in (2)

– 7y + 7(3) = 7

– 7y = – 14

Substitute the value of y = 2 and z = 3 in (1)

x + 2 – 3(3) = – 6

x + 2 – 9 = – 6

x = – 6 + 7

x = 1

The value of x = 1, y = 2 and z = 3