lesson 5-8: problem solving objective: students will complete word problems by factoring then...
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Lesson 5-8: Problem Solving
Objective:
Students will complete word problems by factoring then solving
Steps
►Define Variables
► Translate the equation
►Solve by factoring (set = 0)
► Write sentence
Ex 1:The square of a number minus the numberis 20. Find the number.Number: n n2 –n=20 n2 –n-20=0 (n-5)(n+4) =0 n=5 or n=-4
Example 2:The width of a rectangle is 5 cm less than
the length. The area is 24 cm2. Find the
dimensions.
1) length: x
width: x – 5
2) x(x-5) = 24
3) x2 -5x - 24 =0
(x - 8)(x + 3)=0
x = 8 or x = -3
4) The length is 8cm and the width is 3 cm
The length can not be negative so the only
solution is 8 cm
A = bh
Ex 3:The sum of the squares of 2 consecutive
odd positive integers is 394. Find the integers.
x2 + (x+2)2 = 394
x2 + x2 + 4x +4 = 394
2x2 + 4x – 390=0
2(x2 +2x – 195)=0
2(x -13)(x+15) = 0
x=13 or x =-15
15
13 1st: x2nd: x +2
Marker Board pg 235
• 2
• 6
• 12
• 16
Assignment
5-8/235-236/1-15o, 24-30
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