Thursday

November 12, 2009

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Algebra 1B!

• Warm – Up• Check Homework• 4-4B Notes• Assignment: 4-4B

Worksheet

Solve these two systems by graphing.

3

2

xy

xy

1052

25

2

yx

xy

I CAN . . .

~solve systems of equations with substitution.

yx

yx

2

822 2(2 – y) + 2y = 8

This is FALSE so that means…….?

No solution (parallel lines)

4 – 2y + 2y = 8

4 = 8

Hint: Get c by itself.

c – 4d = 1

+4d +4d

c = 4d + 1

282

14

dc

dc

2(4d + 1) – 8d = 2

8d + 2 – 8d = 2

0 + 2 = 2

This is TRUE so that means…….?Infinitely many =

Same line

TRUE: such as –5 = –5 False: such as 5 = 8

Solution: ____________ Solution: ____________

Type of line: ___________ Type of line: _________

If your variables “cancel out” and the result is:

Infinitely many

SAME line

No solutions

Parallel

Solution: (2, 6)

1823

4

yx

xy y = x + 4

3x + 2(x + 4) = 18

3x + 2x + 8 = 18

5x + 8 = 18

5x = 10

x = 2

y = 2 + 4

y = 6

624

32

yx

xy

4x + 2(–2x + 3) = 6

4x – 4x + 6 = 6

6 = 6

This is TRUE so that means…….?Infinitely many =

Same line

Sue had two tests on Monday (history and biology). Her biology score was 12 points higher than her history score. The total of her two scores was 154. What was her biology test score?

b = 12 + h

b + h = 154

12 + h + h = 154

12 + 2h = 154–12 –12

2h = 142

h = 71b = 12 + 71

b = 83

Dan bought two new games for his Wii. Super Mario Brothers cost twice as much as Lego Star Wars. The total for both games was $72. What does Lego Star Wars cost?

m = 2L

m + L = 72

2L+ L = 72

3L = 72

L = 24

Lucy is selling girl scout cookies. She sells 4 times as many boxes of Caramel Delites as Thin Mints. Caramel Delites cost $4 per box and Thin Mints cost $3.50 per box. She makes a total of $156. How many boxes of Caramel Delites did she sell?

c = 4m

4c + 3.50m = 156

4(4m) + 3.50m = 156

19.50m = 156

m = 8

c = 4(8)

c = 32

16m + 3.50m = 156

What does an infinitely many solutions mean?

What does a no solution mean?

4-4B Worksheet