Question

Systems of equations with substitution 5x-4y=-10 and y=2x-5

Answer 1

5x-4y=10 .....eq1

y=2x-5 .....eq2

substituting the value of y in eq.1

5x-4 (2x-5)=10

5x-8x+20=10

3x=10

x=10/3

from eq.2

y=2x-5

y=(2×10/3)-5

y=(20/3)-5

y=20-15/3

y=5/3

Answer 2

Here the given equations are :

5 x - 4 y = - 10 •••••••••eq.1

Y = 2 x - 5 •••••••• eq.2

Multiplying eq.2 by 4 ;

Then ;

4 y = 8 x - 20

=> - 8 x + 4 y = - 20•••••••••••eq.3

Now;

Subtracting eq.3 and eq.4 ;

- 8 x + 4 y = - 20

5 x - 4 y = - 10

_______________

- 3 x = 10

=>X = - 10 / 3

Now ; subtituting the value of x in eq. 1

We get ;

5 * -10 / 3 - 4 y = - 10

- 50 / 3 - 4 y = - 10

- 4 y = - 10 + 50 / 3

On taking L.C.M

- 4 y = ( - 30 + 50 ) / 3

- 4 y = - 20 / 3

Y = ( - 20 / 3 ) / - 4

Y = - 20 / - 12

Y = 5/3

Thus ;

X = - 10 / 3

Y = 5 / 3