Find the approximate solution of the given system of equations.
8x + 3y = 9
3x - 5y = 20
a. (3.36, -1.99)
b. (-1.11, 2.79)
C. (0,-1.99)
d. (3.36, 2.79)

x= 2.14 y= -2.71

Step-by-step explanation:

8x + 3y = 9 equ i

3x - 5y = 20equ ii

using substitution method

making x the dsubject of formula in 8x + 3y = 9

8x= 9-3y

x=(9-3y)/8equ iii

insert it in equ ii

3x - 5y = 20

3{(9-3y)/8} - 5y = 20

open the bracket and add 5y to both sides

27-9y/8= 20+5y

cross multiply

27-9y = 8(20+5y)

27-9y = 160+40y

choose like terms

-9y-40y=160-27= 133

-49y=133

y=133/-49= -2.71

insert the value of y back in x=(9-3y)/8

x=(9-3y)/8= 9-3(-2.71)/8= 9+8.14/8= 17.14/8= 2.14

x= 2.14

or  

using elimination system

multiply the coefficient of y (3) in equ i by equation ii

multiply the coefficient of y (5) in equ ii by equation i

5 x 8x + 3y = 9

3 x 3x - 5y = 20

40x+15y=45

9x-15y=60

add each other(since they have different signs + and -)

40x+15y=45

+

9x-15y=60

40x+9x +15y+(-15y) = 45+60

49x = 105

x= 105/49 = 2.14

since x = 2.14 insert it in either equ i or ii

8x + 3y = 9

8(2.14)+3y=9

17.14+3y= 9

17.14-9 = -3y

8.14= -3y

y= 8.14/-3= -2.71

3x - 5y = 20

3(2.14)-5y=20

6.428-5y= 20

6.428-20 = 5y

-13.5714= 5y

y = -13.5714/5 = -2.71

step-by-step explanation:

x=4

step-by-step explanation: