Substitution Jeopardy

Check if Solution

100

Is x = 3, y = -2 the solution to

2x + 4y = 4

x + 9y = 23

No!

2(3) + 4(-2) = -2, not 4.

300

Is x = -1, y = 2 the solution to

-9x - 2y = 5

-10x + y = 12

Yes!

-9(-1) - 2(2) = 9-4 = 5 and

-10(-1) + 2 = 10 + 2 = 12

500

Is x = 3, y = -7 the solution to

-x + y = -10

6x + 5y = -28

No!

While -3 + -7 = -10 (the top one is true), the bottom one is

6(3) + 5 (-7) = 18 - 35 = -17, not -28.

Variable Already by Itself

100

Solve & check:

x = 5 - 10y

-2x - 7y = 3

x = -5, y = 1

300

Solve & Check:

y = 9x - 6

x + 3y = -18

x = 0, y = -6

500

Solve & Check:

x = 10y + 4

3x + 5y = 12

x = 4, y = 0

Solve for a Variable

100

Solve & Check:

3x - 7y = 7

x - 10y = 10

x = 0, y = -1

300

Solve & Check:

-2x + y = -5

-6x + 4y = -24

x = -2, y = -9

500

Solve & Check:

-x + 3y = -5

-2x + 4y = -4

x = -4, y = -3