PLZ HELP ITS 20 POINTS Using the linear combination method, what is the solution to the system of linear equations 5 x + 3 y = negative 10 and Negative 20 x minus 7 y = 15? (–5, 1) (–1, 5) (1, –5) (5, –1)

Mathematics · College · Thu Feb 04 2021

llm

Answered on Sat Jul 23 2022

We have to solve two equations with the linear combination method:

5x +3y = -10

=> 5x + 3y +10

-20x -7y = 15

=> 20x + 7y +15

We have two same variables in both equations, but their constants are different. We have to make a common pair for elimination

• So Firstly, multiple the first equation by -4 to make the x's constant the same:

= -4(5x + 3y +10)

= -20x -12y -10

• Add the equations, which result in eliminating x:

= -20x -12y -10 +20x +7y +15

= -5y +5

5y = 5

y = 5/5

y = 1

• Now put y=1 in equation two,

-20x -7y=15

-20x -7(1) =15

-20x -7 =15

-20x = 15 +7

-20x =22

-x = 22/20

-x = 1.1

x= -1.1

The values are x= -1.1; y= 1.