Question

Solve the following system of equations:

-2x + y = 1
-4x + y = -1

(3, 1)

(-1, 3)

(-1, -3)

(1, 3)

Answer 1

@undeadknight

Answer 2

@Jadeishere

Answer 3

Dude substitute the coordinates into the variables

Answer 4

when it gives you options it's easy

Answer 5

howwwwww

Answer 6

Just rewrite the problem

Answer 7

do you prefer elimination or substitution ?

Answer 8

idk im pretty terrible at anything having to do with algebra

Answer 9

so it would be -1, 3

Answer 10

right?

Answer 11

Ok whats -2*-1+3

Answer 12

-2x + y = 1 --->(-1)
-4x + y = -1
-------------
2x - y = -1 (result of multiplying by -1)
-4x + y = -1
-------------add
-2x = -2
x = 1
now sub 1 in for x in either equation to find y
-2x + y = 1
-2(1) + y = 1
-2 + y = 1
y = 1 + 2
y = 3

check..
-4x + y = -1
-4(1) + 3 = -1
-4 + 3 = -1
-1 = -1 (correct)
solution is : (1,3)

Answer 13

any questions ?

Answer 14

that was solved by elimination...would you like me to show you how to solve it with substitution ?

Answer 15

yea can ou help me with another

Answer 16

I can

Answer 17

Solve the following system of equations:

x - 2y = 14
x + 3y = 9

(1, 12)

(-1, -12)

(12, -1)

(12, 1)

Answer 18

substitution or elimination ?

Answer 19

I will do substitution, so you can see how both ways work...give me a sec

Answer 20

it doesnt matter to me

Answer 21

x - 2y = 14
x = 2y + 14
now sub 2y + 14 in for x in the other equation
x + 3y = 9
2y + 14 + 3y = 9 -- subtract 14 from both sides
2y + 3y = 9 - 14 -- combine like terms
5y = - 5
y = -1
now sub -1 in for y in either equation to find x
x - 2y = 14
x - 2(-1) = 14
x + 2 = 14
x = 14 - 2
x = 12
check..
x + 3y = 9
12 + 3(-1) = 9
12 - 3 = 9
9 - 9 (correct)
solution is : (12,-1)

Answer 22

wow thanks

Answer 23

Determine which system below will produce infinitely many solutions.

2x + 5y = 24
2x + 5y = 42

3x - 2y = 15
6x + 5y = 11

4x - 3y = 9
-8x + 6y = -18

5x - 3y = 16
-2x + 3y = -7

Answer 24

4x - 3y = 9
-8x + 6y = -18 reduces to -4x + 3y = -9

so we now have :
4x - 3y = 9
-4x + 3y = -9
------------add
0 = 0

INFINITELY MANY SOLUTIONS -- answer is C

Answer 25

Solve the system of equations.

5x + y = 9
3x + 2y = 4

(-2, 5)

(1, 4)

(2, -1)

(4, -4)

Answer 26

y = -5x + 9
now sub -5x + 9 in for y in the other equation
3x + 2y = 4
3x + 2(-5x + 9) = 4
3x -10x + 18 = 4
3x - 10x = 4 - 18
-7x = -14
x = 2
now sub 2 in for x in either equation to find y
y = -5x + 9
y = -5(2) + 9
y = -10 + 9
y = -1
check..
3x + 2y = 4
3(2) + 2(-1) = 4
6 - 2 = 4
4 = 4 (correct)

solution is : (2,-1)