Question

4. The solution of 3x - 5y = -16 and 2x + 5y = 31
a. X=-3, y=5
b. X=-3, y=-5
c. x= 3, y = -5
d. x= 3, y = 5
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Answer 1

The given equations are 

3x−5y=−16           (1)

2x+5y=31           (2)

Note that the coefficients of y in both equations are numerically equal. So, we can eliminate y easily. 

Adding (1) and (2), we obtain an equation

5x=15

That is, x=3      (3)

Now, we substitute x = 3 in (1) or (2) to solve for y.   

Substituting x = 3 in (1) we obtain, 3(3)−5y=−16

→y=5

Now, (3, 5) a is solution to the given system because (1) and (2) are true when x = 3   and y = 5  as from (1) and (2) we get,  3(3)−5(5)=−16 and 2(3)+5(5)=31.  

Answer 2

Answer:

3x-5y=-16....(1)

2x+5y =31 .,....(2)

Explanation:

3x-5y=-16=>6x-10y=-32

2x+5y=31=>6x+15y=93

25y=125 => y=5

x=3