Question

Use the solution method to the system of equations 8x+5y=9 , y=x+7

Answer 1

x = -2

y = 5

Explanation:

8x+5y=9 ........... (i)

y=x+7 ..................(ii)

Substitute (y = x + 7) in equation (I)

8x + 5(x + 7) = 9

8x + 5x + 35 = 9

13x + 35 = 9

13x = 9 - 35

13x = -26

Divide both sides by 13 to make x the subject :

x = -26 / 13

x = -2

Substitute x = -2 in equation (ii)

y = x + 7

y = -2 + 7

y = 5.

TO CHECK:

x = -2

y = 5

8x+5y=9

8(-2) + 5(5) =

-16 + 25 = 9.

Answer 2

`x=-2\\y=5`

Explanation:

Given Equations:

`8x+5y=9` Equation:1

`y=x+7` Equation:2

Using substitution method:

Put the value of 'y' in Equation:1

`8x+5y=9`

`8x+5(x+7)=9\\\\8x+5x+35=9\\`

Adding the like terms:

`13x+35=9`

Subtracting '35' both sides:

`13x+35-35=9-35\\\\13x=-26\\`

Dividing '13' both sides:

`x=-26/13\\\\x=-2`

Put the value of 'x' in Equation:2

`y=x+7`

`y=-2+7\\\\y=5`

The solution of the equation is:

`x=-2\\y=5`