Question

Solve the following system of equations y + 4x = 8 and 5x + 2y = 13

(A) 1, 4
(B) 3/2, 1/2
(C) -1/2, 4

Answer 1

y + 4x = 8....y = -4x + 8

5x + 2y = 13
5x + 2(-4x + 8) = 13
5x - 8x + 16 = 13
-3x = 13 - 16
-3x = -3
x = -3/-3
x = 1

y + 4x = 8
y + 4(1) = 8
y + 4 = 8
y = 8 - 4
y = 4

solution is (1,4)

Answer 2

the order Ax + By = constant we have 4x + 1y = 8, and 5x + 2y = 13 dropping x,y

4 1 8
5 2 13
multiply the top row by -5/4 and add to the 2nd row
4 1 8
0 3/4 3

back solve
3/4y = 3
y = 4

use the first row, y = 4
4x + 4 = 8
x = 1
the answer is : a. 1,4

hope this help