Algebra Honors ( Periods 4 & 7)

Applying Systems of Linear Equations 6-5

METHOD	BEST TIME to USE
Graphing	estimate solutions
Substitution	If one of the variables has a coefficient of +1 or -1
Elimination Add/Sub	If one of the variables has opposite or same coefficient in both equations
Elimination Multiplication	If none of the coefficients are +1 or -1 & neither of the variables can be eliminated by addition or subtraction

What would the best method? Now find the solution..:

2x + 3y = -11

-8x -5y = 9

Answer: Elim (x)   (2, -5)

3x + 4y = 11

2x + y = -1

Answer: Substitution  ( -3, 5)

3x -4y = -5

-3x + 2y = 3

Answer” Elim (+)  ( -1/3, 1)

We are working with word problems. Turn to your textbook Page 367

#5

4 T- shirts  3 pairs of jeans $181

1 T-shirt  2 pairs of jeans $94

Let statements help keep you organized so

Let T = the cost of each of the T-shirts

Let J = the cost of each of the pairs of jeans

4T  + 3J = 181

1T  + 2J = 94

using substitution you find T = 94-2J

substitute in

4(94 – 2J ) + 3J = 181

J = $39.00

T = $16

#14

The Caverns of Sonora have two different tours: The Crystal Palace tour and the Horseshoe Lake Tour. The total length of both tours is 3.25miles. The Crystal Palace Tour is one-half mile less than twice the distance of the Horseshoe Lake Tour.  Determine the length of each tour.

Let C = the length in miles of the Crystal Palace tour

Let H= the length in miles of the Horseshoe Lake tour

 C + H = 3.25

C = 2H -0.5

substitution

2H-0.5 + H = 3.25

3H = 3.75

H = 1.25

so C = 2

Horseshoe Lake Tour is 1.25miles and Crystal Palace Tour is 2 miles

# 15

The breakeven point is the point at which income = expenses

Ridgemont High school is paying $13,200 for the writing and research of their yearbook plus a printing charge of $ 25 per book.  If they sell the books for $ 40 each, how many will they have to sell to break-even?

I would probably just use one equation but since we are in systems, I will set this up using two variables.

Let b = the number of books

Let p = the breakeven point

$13,200 + 25b = p

40b = p

$13,200 + 25b= 40b

880 books