Question

Solve each of the following pairs of equation by the substitution method
8x+5y=9
3x+2y=4

Answer 1

(8x+5y=9)3=>24x+15y=27 ------(1)
(3x+2y=4)8=>24x+16y=32 ---(2)
from (2)-(1)
y=5
substitution
3x+2 (5)=4
3x+10=4
3x=4-10
3x=-6
x=-2

Answer 2

Given equations;

8x+5y = 9
3x+2y = 4

3x+2y = 4
3x = 4-2y
x = (4/3)-(2/3)y

8x+5y = 9
8[(4/3)-(2/3)y] + 5y = 9
(32/3) - (16/3)y+5y = 9
(1/3)y = (5/3)
y = 5

x = (4/3)-(2/3)y
= (4/3)-5(2/3)
= (4/3) - (10/3)
= -6/3
= -2
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