5. 3x + 5y + 5z =1
x - 2y = 5
2x + 4y = 11

see explanation

Step-by-step explanation:

Given the 3 equations

3x + 5y + 5z = 1 → (1)

x - 2y = 5 → (2)

2x + 4y = 11 → (3)

Use (2) and (3) to solve for x and y

Multiply (2) by 2

2x - 4y = 10 → (4)

Add (3) and (4) term by term

4x = 21 ( divide both sides by 4 )

x =

Substitute this value of x into (3)

2 × + 4y = 11

+ 4y = 11 ( subtract from both sides )

4y = ( divide both sides by 4 )

y =

Substitute the values of x and y into (1) and solve for z

3 × + 5 × + 5z = 1

+ + 5z = 1

+ 5z = 1 ( subtract from both sides )

5z = - ( divide both sides by 5 )

z = -

Solution is

x = , y = , z = -

b

step-by-step explanation:

the word superfluous means unnecessary