Lesson 2C. Solving Quadratic Equations by Completing the Square
Activity 1: PST to Square of a Binomial!
Let's further strengthen your knowledge and skills in writing perfect square trinomials by doing the next activity.
Activity 2:
Make It Perfect!
TIP: Add a square of one half of the coefficient of the middle term.
(b/2)^2
Making Perfect Square Trinomials
Divide both sides of the equation by a then simplify.
Write the equation such that the terms with variables are on the left side of the equation and the constant term is on the right side.
Add the square of one half of the coefficient of x on both sides of the resulting equation. The left side of the equation becomes a perfect square trinomial.
Express the perfect square trinomial on the left side of the of the equation as a square of a binomial.
Solve the resulting quadratic equation by extracting the square root.
Solve the resulting linear equations.
Check the solutions obtained agains the original equation.
EXAMPLES
Activity 3:
Let's Practice!
Was it easy for you to find the solutions of the quadratic equations by completing the square?
Now, let's get deeper!
Please Watch This!
Perform the following activity.
Make sketch plans of 5 rectangular boxes such that:
a. the heights of the boxes are the same; and
b. the boxes can hold 240 cubic cm, 270 cubic cm, 504 cubic cm, 810 cubic cm, and 468 cubic cm, respectively.
Write a quadratic equation that would represent the volume of each box.
Solve each quadratic equation by completing the square to determine the dimensions of the materials to be used in constructing each box.
Make sketch plans of covers of the open boxes in Part A such that:
a. the heights of the covers are the same; and
b. the base of each cover is rectangular.
Write a quadratic equation that would represent the volume of the box's cover.
Solve each quadratic equation by completing the square to determine the dimensions of the materials to be used in constructing the box's cover.