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

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Assignment

5-8/235-236/1-15o, 24-30