Question

5x – 6y + 30 = 0 ; 5x + 4y -20 = 0 solve these simultaneous equation graphically

Answer 1

Answer:

1. x = 24

y = 25

2. x = 16

y = -15

Step-by-step explanation:

5x – 6y + 30 = 0

$5x - 6y = - 30 \\(5 \times x) - (6 \times y) = - 30 \\x - y = - 30 \div 30 \\x - y = - 1 \\ x = -1 + y \: or \: x = y - 1$

Now substitute x value in the expression

$5(y - 1) - 6y + 30 = 0 \\5y - 5 - 6y + 30 = 0 \\ - y + 25 = 0 \\ - y = - 25 \: or \: y = 25$

Evaluate value of x

$y = 25 \\x = y - 1 = 25 - 1 = 24$

5x + 4y -20 = 0

$5x + 4y = 20 \\x + y = 20 \div 20 \\x + y = 1 \\ x = 1 - y$

Substitute x value in the expression

$5(1 - y) + 4y - 20 = 0 \\5 - 5y + 4y = 20 \\5 - y = 20 \\ - y = 15 \: or \: y = - 15$

Evaluate value of x

$y = - 15 \\x = 1 - y = 1 - - 15 = + 15 = 16$