7.7k views
3 votes
Solve each system by substitution

Solve each system by substitution-example-1
User Somdoron
by
8.3k points

2 Answers

2 votes

\left \{ {{-3x-3y=3\:(I)} \atop {y=-5x-17\:(II)}} \right.
Replace the equation y in the first equation.

-3x-3y=3 (I)

-3x-3*(-5x-17)=3

-3x+15x+51=3
Now, put the numbers with letter (incognito) to the right and numbers without letter to the left, changing the signal when changing sides.

-3x+15x=3-51

12x = -48

x = (-48)/(12)

\boxed{\boxed{x = - 4}}\end{array}}\qquad\quad\checkmark


Now substitute the found value "x" in the equation y (second equation):

y=-5x-17\:(II)

y = - 5*(-4) - 17

y = 20 - 17

\boxed{\boxed{y=3}}\end{array}}\qquad\quad\checkmark

Answer:

\underline{\textbf{The\:values\​\:found\:are:\:X = -4\:and\: Y = 3} }

User Buntylm
by
8.1k points
2 votes
-3x-3y=3
y=-5x-17----------use this to substitute for y

-3x-3(-5x-17)=3----------like this
-3x+15x+51=3-------------combine like terms
12x+51=3------------subtract 51 both sides
12x=-48---------divide by 12 each side to get x by itself
x=-4

y=-5(-4)-17--------------------substitute the -4 for x to find y
y=3

now we plug in both to see if it works:
-3(-4)-3(3)=3--------------We plug in to see if both answers work
12-9=3----------------It works
(-4,3)

Hope this helps :)
User Shalisha
by
7.5k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories