Do Now 10/15/10

Take out HW from last night.Textbook p.179-181 #4-36 even

Copy HW in your planner.Textbook p. 187 #4-30 even“Pop” Quiz sections 3.5-3.8 Tuesday

HomeworkHomework Textbook p.179-181 #4-36 even Textbook p.179-181 #4-36 even

4) 55% 6) 51 8) 21 10) 44% 12) 27 14) 176.3 16) 210 18) 137.5 20) p% should be multiplied

by 95; p% = 20% 22) 85% 24) 33.8

26) 16% 28) 72% 30) Equation; multiply the

base times the percent to find the part.

32) 5y 34) 200 laps 36)

Year Hikers who Started

Hikers who Completed

Percent Completion

2001 2380 395 16.6%

2002 1880 376 20%

2003 1750 352 20%

Objective

SWBAT rewrite equations and formulas

Section 3.8, “Rewrite Equations Section 3.8, “Rewrite Equations and Formulas”and Formulas”

Literal Equation-Literal Equation-an equation where the coefficients an equation where the coefficients

and constants are replaced by letters. and constants are replaced by letters.

The equation The equation 22x + x + 55 = = 1111 has the general form has the general form aax + x + bb = = cc. .

Solving a Literal EquationSolving a Literal Equation

Subtract b from each side.

Write original equation.

Solve ax + b = c for x.STEP 1

SOLUTION

Solve ax +b = c for x. Then use the solution to solve 2x + 5 = 11.

xc – b

a=

ax + b = c

ax = c – b

Assume a 0. Divide each side by a.=

The solution of 2x + 5 = 11 is 3.ANSWER

Simplify.

Substitute 2 for a, 5 for b, and 11 for c.

Solution of literal equation.

Use the solution to solve 2x + 5 = 11.STEP 2

11 – 52=

x = c – b

a

= 3

Solving a Literal EquationSolving a Literal Equation

Try It OutTry It Out

Subtract a from each side.

Write original equation.

Solve a – bx = c for x.STEP 1

SOLUTION

1. Solve a – bx = c for x.

xa – c

b=

a – bx = c

– bx = c – a

Assume b 0. Divide each side by – 1b.=

Solve the literal equation for x . Then use the solution to solve the specific equation

Try It OutTry It Out

The solution of 12 – 5x = –3 is 3.ANSWER

Simplify.

Substitute a for 12, –3 for c, and 5 for b.

Solution of literal equation.

Use the solution to solve 12 – 5x = –3.STEP 2

12 – (–3)5=

x = a – c

b

= 3

Try It OutTry It Out

Subtract bx from each side.

Write original equation.

Solve a x = bx + c for x.STEP 1

SOLUTION

2. Solve a x = bx + c for x.

cx

a – b=

a x = bx + c

a x – bx = c

Assume a 0. Divide each=side by a – b.

Try It OutTry It Out

The solution of 11x = 6x + 20. is 4.ANSWER

Simplify.

Solution of literal equation.

Use the solution to solve 11x = 6x + 20.STEP 2

2011 – 6=

x = c

a – b

= 4

Substitute a for 11, 20 for c, and6 for b.

Rewriting Equations with Multiple Variables

An equation or formula with 2 or more An equation or formula with 2 or more variables, such as variables, such as 3x + 2y = 83x + 2y = 8 or or A = ½bhA = ½bh, , can be rewritten so that one variable is a can be rewritten so that one variable is a function of the other variable(s). function of the other variable(s).

3x + 2y = 83x + 2y = 8This equation can be rewritten so that y is a function of x.

A = ½bhA = ½bhThis equation can be rewritten so that you can solve for h.

Try It Out

Divide each side by 2.

Write original equation.

Write 3x + 2y = 8 so that y is a function of x.

Subtract 3x from each side.

3x + 2y = 8

2y = 8 – 3x

32

y = 4 – x

Try It OutTry It Out

Multiply each side by 2.

Write original formula.

SOLUTION

Solve the formula for the height Solve the formula for the height hh..a. a.

The area The area AA of a triangle is given by the formula of a triangle is given by the formula A A = = bhbh where where bb is the base and is the base and hh is the height.is the height.

1122

a. bh12A =

2A bh=

Divide each side by b.2A b

h=

Try It OutTry It Out

Substitute 64.4 for A and 14 for b.

Write rewritten formula.

Substitute 64.4 for A and 14 for b in the rewritten formula.

= 2(64.4) 14

= 9.2 Simplify.

ANSWER The height of the triangle is 9.2 meters.

h2A b=

Use the rewritten formula to find the Use the rewritten formula to find the height of the triangle shown, which height of the triangle shown, which has an area of has an area of 64.464.4 square meters. square meters.

b. b.

Rewrite the following Rewrite the following formulas formulas in in terms for each variable.terms for each variable.

Temperature Temperature Distance TraveledDistance Traveled

ProfitProfit Simple InterestSimple Interest

)32(9

5 FC

EIP tI Pr

rtd

Temperature Temperature Distance TraveledDistance Traveled

ProfitProfit Simple InterestSimple Interest

)32(9

5 FC

EIP tI Pr

rtd 32

5

9 CF

t

dr

r

dt

EPI PIE rt

IP

Pt

Ir

Pr

It

Challenge

The surface area of a cone is given by the formula below. Solve for the length.

2rrlS

rr

Sl