Thursday
November 12, 2009
Welcome
to
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