Question Details

Find the value of x, y, z for the given system of equations : 2x+3y+2z=50, x+4y+3z=40, 3x+3y+5z=60

Options

A

x=125/8, y=15/2, z=15/8

B

x=125/8, y=15/2, z=-(15/8)

C

x=125/8, y=-(15/2), z=-(15/8)

D

x=-(125/8), y=15/2, z=-(15/8)

Correct Answer :

x=125/8, y=15/2, z=-(15/8)

Solution :

The correct option is: x=125/8, y=15/2, z=-(15/8).

To find the values of x, y, and z, we can solve the given system of linear equations step-by-step:

Equation 1:
2 x + 3 y + 2 z = 50

Equation 2:
x + 4 y + 3 z = 40

Equation 3:
3 x + 3 y + 5 z = 60

Step 1: Eliminate one variable from the equations.
Let us eliminate x using Equation 2. From Equation 2, we can express x in terms of y and z:
x = 40 4 y 3 z

Step 2: Substitute this expression for x into Equation 1 and Equation 3.

Substituting into Equation 1:
2 ( 40 4 y 3 z ) + 3 y + 2 z = 50
Simplifying:
80 8 y 6 z + 3 y + 2 z = 50
80 5 y 4 z = 50
Subtract 80 from both sides:
5 y 4 z = 30
Multiplying by -1 gives Equation 4:
5 y + 4 z = 30

Substituting into Equation 3:
3 ( 40 4 y 3 z ) + 3 y + 5 z = 60
Simplifying:
120 12 y 9 z + 3 y + 5 z = 60
120 9 y 4 z = 60
Subtract 120 from both sides:
9 y 4 z = 60
Multiplying by -1 gives Equation 5:
9 y + 4 z = 60

Step 3: Solve the system of two equations (Equation 4 and Equation 5).

Subtract Equation 4 from Equation 5:
( 9 y + 4 z ) ( 5 y + 4 z ) = 60 30
4 y = 30
y = 30 4 = 15 2

Step 4: Find z using the value of y.
Substitute y=152 into Equation 4:
5 ( 15 2 ) + 4 z = 30
75 2 + 4 z = 30
4 z = 30 75 2
4 z = 60 2 75 2
4 z = 15 2
z = 15 8

Step 5: Find x using the values of y and z.
Substitute y=152 and z=158 into Equation 2:
x + 4 ( 15 2 ) + 3 ( 15 8 ) = 40
x + 30 45 8 = 40
x = 40 30 + 45 8
x = 10 + 45 8
x = 80 8 + 45 8
x = 125 8

Thus, the final values are x=1258, y=152, and z=158.

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