Question

X+2y=5

X-3y=7

What is the value of the system determinant?

A) -5
B) 1
C) 5

Answer 1

The answer is B) 1

Explanation:

x-2y=5 x-3y=7

+2y=+2y

x-0=5+2y

x=5+2y

This problem says x is 5+2y, so substitute 5+2y for x in the other problem:

x-3y=7 1. Put 5+2y in place of the x:

(5+2y)-3y=7 2. Now, remove the parenthesis:

5+2y-3y=7 3. Combine the y's:

5-y= 7 (2y-3y=-y) 4. Solve for y:

-5 =-5

0-y= 2

- (1)y= 2

-1

y=-2

5. Now that you know y is -2, you can put it in your problems to solve for x:

x-3y=7 x-2y=5

x-3(-2)=7 x-2(-2)=5

x+6= 7 x+4= 5

-6=-6 -4=-4

x=1 x=1