Select all the systems of equations that have exactly one solution. y = 3x + 1
y = 3x + 7

y = 3x + 1
y = x+1

y=3x+1
y = 3x + 7

x+y=10
2x+2y=20

x+y=10
x+y=12

b) y = 3x + 1

y = x+1

Step-by-step explanation:

Select all the systems of equations that have exactly one solution.

a)

y = 3x + 1

y = 3x + 7

y - 3x = 1 Equation 1

y - 3x = 7 Equation 2

We solve using Elimination

We Subtract Equation 2 from 1

(y - y ) - (3x - 3x) = 7 - 1

0 = 6

b) y = 3x + 1 Equation 1

y = x +1 Equation 2

x = y - 1

We substitute y - 1 for x in Equation 1

y= 3(y - 1) + 1

y = 3y - 3 + 1

y - 3y = -3 + 1

-2y = -2

y = -2/-2

y = 1

Solving for x

x = y - 1

x = 1 - 1

x = 0

x = 0, y = 1,

The Equations in b) have only one solution

c) x+y=10

x = 10 - y

2x+2y=20

We substitute

2(10 - y) + 2y = 20

20 - 2y + 2y= 20

-2y + 2y = 20 - 20

0 = 0

It has no solution

d) x+y=10 Equation 1

x+y=12 Equation 2

We solve using Elimination

We Subtract Equation 2 from 1

x - x + y - y = 12 - 10

0 = 2

answer: a video game has three difficulty levels: easy, medium, and expert. the game's scoring works in such a way that a player has to score a fixed number of points to advance to the next level, and then the scoring starts over. the total score needed to clear all three difficulty levels is 7,500. two times the number of points needed to clear the easy level is 500 more than the number of points needed to clear the medium level. twice the number of points needed to clear the medium difficulty level is 1,500 more than the number of points needed to clear the expert level. if x, y, and z represent the easy, medium, and expert levels, respectively, and a is the coefficient matrix of the system of equations modeling this situation, identify the inverse matrix, a-1, and the solution matrix, x, of the system of equations.

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