ALGEBRA I

Lesson 6: Solving Basic One-Variable Quadratic Equations S.1This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from ALG I-M4-TE-1.3.0-09.2015

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Lesson 6: Solving Basic One-Variable Quadratic Equations

Classwork

Example 1

A physics teacher put a ball at the top of a ramp and let it roll down toward the floor. The class determined that the height of the ball could be represented by the equation h( t)=−16 t 2+4, where the height, h( t), is measured in feet from the ground and time, t , is measured in seconds.

a. What do you notice about the structure of the quadratic expression in this problem?

b. In the equation, explain what the 4 represents.

c. Explain how you would use the equation to determine the time it takes the ball to reach the floor.

d. Now consider the two solutions for t . Which one is reasonable? Does the final answer make sense based on this context? Explain.

Lesson 6 M4NYS COMMON CORE MATHEMATICS CURRICULUM

ALGEBRA I

Lesson 6: Solving Basic One-Variable Quadratic Equations S.2This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from ALG I-M4-TE-1.3.0-09.2015

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

2. The length of a rectangle is 5∈. more than twice a number. The width is 4∈. less than the same number. The perimeter of the rectangle is 44∈¿. Sketch a diagram of this situation, and find the unknown number.

3. The length of a rectangle is 5∈. more than twice a number. The width is 4∈. less than the same number. If the

area of the rectangle is 15¿2, find the unknown number.

ExercisesSolve each equation. Some of them may have radicals in their solutions.

1. 3 x2−9=0 2. (x−3)2=1 3.

4 (x−3)2=1

Lesson 6 M4NYS COMMON CORE MATHEMATICS CURRICULUM

ALGEBRA I

Lesson 6: Solving Basic One-Variable Quadratic Equations S.3This work is derived from Eureka Math ™ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org This file derived from ALG I-M4-TE-1.3.0-09.2015

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

ExercisesSolve the following problems. Be sure to indicate if a solution is to be rejected based on the contextual situation.

4. The length of a rectangle is 4 cm more than 3 times its width. If the area of the rectangle is 15cm2, find the width.

5. The ratio of length to width in a rectangle is 2 ∶ 3. Find the length of the rectangle when the area is 150¿2.

Lesson 6 M4NYS COMMON CORE MATHEMATICS CURRICULUM