Question

Solve the following simullateneous equation using a algebraic method (not graphically)

2x+5y=0
3x-4y=23

Answer 1

x = 5

y = -2

Explanation:

to solve this simultaneous equation using substitution method

solution

let

2x+5y=0............................. equation 1

3x-4y=23.................................. equation 2

from equation 1

2x+5y=0............................. equation 1

2x = -5y

divide both sides by the coefficient of x which is 2

we have,

2x/2 = -5y/2

x = -5y/2 ............................................. equation 3

substitute for x = -5y/2 in equation 2

3x-4y=23.................................. equation 2

3 ( -5y/2) - 4y = 23

-15y/2 - 4y = 23

multiply through by 2

-15y - 8y = 46

-23y = 46

divide both sides by the coefficient of y which is -23

-23y/-23 = 46/-23

y = -2

put the value of y = -2 into equation 3

x = -5y/2 ............................................. equation 3

x = -5 (-2)/ 2

x = 10/2

x = 5

therefore the value of x = 5 and y = -2 respectively