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Solve the following system of equations using the substitution method.
y = -5x - 17
-3x - 3y = 3
O A) (-4,-3)
B) (-4,3)
C) (4,3)
D) (4,-3)

Respuesta :

Answer:

[tex]\boxed {\boxed {\sf (B. \ -4, 3)}}[/tex]

Step-by-step explanation:

We are given 2 equations and asked to solve the system of equations using the substitution method.

The 2 equations are:

[tex]y= -5x-17 \\-3x-3y= 3[/tex]

The first equation is already solved for y, so we can substitute -5x-17 (the expression that y is equal to) into the second equation.

[tex]-3x-3(-5x-17)=3[/tex]

Solve for x by isolating the variable. First, distribute the -3. Multiply each term in parentheses by -3.

[tex]-3x + [ (-3*-5x ) \ + \ (-3* -17)][/tex]

[tex]-3x + [15x + 51]= 3[/tex]

[tex]-3x+15x+51=3[/tex]

Combine like terms. -3x and 15x can be added because both terms contain the variable x.

[tex]12x+51=3[/tex]

51 is being added to 12x. The inverse operation of addition is subtraction. Subtract 51 from both sides of the equation.

[tex]12x+51-51=3-51[/tex]

[tex]12x= -48[/tex]

x is being multiplied by 12. The inverse operation of multiplication is division. Divide both sides by 12.

[tex]\frac {12x}{12}= \frac{-48}{12}[/tex]

[tex]x= -4[/tex]

Now that we have solved for x, we must find y. We know that x is equal to -4, so we can substitute -4 in for x in the first equation.

[tex]y= -5x-17[/tex]

[tex]y= -5(-4)-17[/tex]

Multiply.

[tex]y=20-17[/tex]

Subtract.

[tex]y=3[/tex]

Coordinate points are written as (x, y), so the solution to this system of equations is (-4, 3)