Question

Solve the simultaneous equations 3x- 4y =20 and 4x-2y = 25

Answer 1

Answer:

The x is 6 the y is -0.5

Step-by-step explanation:

3x-4y=20

4x-2y=25

Multiply the bottom equation by 2.

3x-4y=20

8x-4y=50

Subtract the first equation from the second and that will equal the subtraction of the first answer from the second.

(8x-4y) - (3x-4y) = 50 - 20

Simplify.

5x = 30

Divide both sides by 5.

x = 6

Plug the x in for the first equation.

3*6-4y=20

18-4y=20

Subtract 18 from both sides.

-4y=2

Divide both sides by -4.

y = -0.5

Answer 2

Answer:

(6, - $\frac{1}{2}$ )

Step-by-step explanation:

Given the 2 equations

3x - 4y = 20 → (1)

4x - 2y = 25 → (2)

Multiplying (2) by - 2 and adding to (1) eliminates the y- term

- 8x + 4y = - 50 → (3)

Add (1) and (3) term by term to eliminate y

- 5x = - 30 ( divide both sides by - 5 )

x = 6

Substitute x = 6 into either of the 2 equations and evaluate for y

Substituting into (1)

3(6) - 4y = 20

18 - 4y = 20 ( subtract 18 from both sides )

- 4y = 2 ( divide both sides by - 4 )

y = $\frac{2}{-4}$ = - $\frac{1}{2}$

Solution is (6, - $\frac{1}{2}$ )