Help! Can anyone solve these equations by using the substitution method?

Question

1. 3x - 4y = - 5
-x + 3y = -5

2. 6x - 3y = 15
-2x + y = -5

Thank you.

Answer 1

1. make the second equation look like:
x= 3y + 5
so the first equation is now
3(3y +5) -4y = -5
9y +15 - 4y = -5
5y = -20
y = -4
sub the new y back into your rearranged second equation
x = 3(-4) +5
x = -12 + 5
x = -7
ANSWER (-7,-4)

2. rearrange second eqn to look like:
y = 2x-5
plug into first eqn
6x - 3(2x-5) = 15
6x - 6x + 15 = 15
0 = 0
THESE TWO EQUATIONS ARE THE SAME LINE... so infinite answers

Answer 2

so to use the substitutio method you have to solve for one variable then substitute it into the other equation.

1. 3x - 4y = - 5
-x + 3y = -5
so solve for x in the second equation:
x=3y+5
substitute (3y+5) into the other equation for x:
3(3y+5)-4y=-5
9y+15-4y= -5
5y= -20
y= -4
substitute that into ay of the equations and solve for x:
x=3y+5
x=3(-4)+5
x= -7
x= -7 and y= -4

2. 6x - 3y = 15
-2x + y = -5
For this one it is easier to take the second equation and solve for y:
y=2x - 5
Substitute (2x -5) into the first euation for y:
6x- 3(2x -5)=15
6x -6x -15 =15
0=0
there are infnate answers for the sexond question because the equations are the same line.

I think that was a pretty good answer...maybe it even deserves 10 points ;) lol

Answer 3

1) 3x - 4y = -5
-x + 3y = -5

just add similar terms:
3x - 4y = -5
+ -x + 3y = -5
-------------------
2x -y = -10
y = 2x + 10

substitute y any of the given equations

3x - 4(2x + 10) = -5
3x -8x -40 = -5
-5x = 40 - 5
-5x = 35
x = 35/-5
x = -7

substitute x any of the given equations to get y.

-(-7) + 3y = -5
7 + 3y = -5
3y = -5 - 7
y = -12/3
y = -4

ANSWER: x = -7 y= -4

Answer 4

4x-4y=4 it rather is easy. this popular a multipultication concern. endure in recommendations x and y characterize numbers. the 1st ingredient you desire to do is multiply 4*x then multiply 4*y. right it rather is a touch y=one million. So 4*x=? 4*one million=4? So 4*x - 4 = 4. what's the backside quantity you are able to multiply 4 circumstances to get an answer of four for the equation. -2x + 3y = 5 it rather is first a mulitpultication concern. endure in recommendations once you multiply a destructive quantity circumstances a destructive quantity you get a favorable quantity. So what might you do to alter -2 right into a favorable quantity?

Answer 5

Question 1
x = 3y + 5
3(3y + 5) - 4y = - 5
9y + 15 - 4y = - 5
5y = - 20
y = - 4

3x + 16 = - 5
3x = - 21
x = - 7

x = - 7 , y = - 4

Question 2
Equations are the same.

Answer 6

1.)
3x - 4y = - 5
-x + 3y = -5

x=5+3y sub in eqn 1
15+9y-4y = -5
5y= -20 y = -4

sub y= -4 in eqn 2
x=5-12; x=-7
x=-7 ; y= -4

2.)
6x - 3y = 15
-2x + y = -5

ths has infitine answers..