Completing the Square Practice Questions

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The discussion focuses on completing the square as a method for solving quadratic equations. Participants express a need for guidance on this topic, with one user seeking step-by-step explanations for practice questions. Key concepts like parabolas and vertices are introduced, and examples of completing the square are provided, such as transforming x² - 6x + 10 into (x - 3)² + 1. Additionally, the quadratic formula is mentioned as an alternative method for solving equations. The thread concludes with practice questions for users to work on independently.
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http://img114.exs.cx/img114/3245/untitled10ff.jpg

see if any of you guys can solve a few of these.. if you guys can show me the steps so that i can study them for any of my future tests that would be great. :eek:
 
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valentines said:
see if any of you guys can solve a few of these.. if you guys can show me the steps so that i can study them for any of my future tests that would be great. :eek:
16. Do you know what a parabola is?? Do you know what a vertex is?

17. Can you complete the square?

18. This is more of trial and error than a formula.

19. Pretend the 'more than or equal to' sign is an equal sign and then solve.

20. Can you use the quadratic equation or factorise?

If you know any of this I can start to help, if not I need to explain it. :smile:

The Bob (2004 ©)
 
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The Bob said:
16. Do you know what a parabola is?? Do you know what a vertex is?

17. Can you complete the square?

18. This is more of trial and error than a formula.

19. Pretend the 'more than or equal to' sign is an equal sign and then solve.

20. Can you use the quadratic equation or factorise?

If you know any of this I can start to help, if not I need to explain it. :smile:

The Bob (2004 ©)

nope. i have no idea what I am doing.
:cry:

edit: actually, i know what a vertex is.

i don't know what a parabola is though :bugeye:
 
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A parabola is what you get when you draw the function y = x2. Do you know what that looks like?

Lets say you have x2 - 6x + 10. Completing the square would make the equation like this: (x - 3)2 + 10 - 9 = (x - 3)2 + 1. All that has happened is the -6x has been halved and put in brackets and then the new number (-3) has been squared and taken away from the 10.

Try completing the sqaure of x2 - 10x + 30. Completing the sqaure is also needed for 19.

18. I would use the quadratic forumla : \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} but I think it will want you to complete the square.

Question 20 can be factorise from 2x2 - 7x - 15 = 0 to (2x + 3)(x - 5) = 0 and then you have some values to use.

The Bob (2004 ©)
 
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I need to go sleep now but here are some completing the square question, for you, for practise and I am sure someone else will say if they are right or wrong for you:

y = x2 - 8x + 20
y = x2 - 4x + 7
y = x2 + 2x + 2
y = x2 + 4x + 2
y = x2 - 10x + 25

Good Luck and I will read what you have done tomorrow. :smile:

The Bob (2004 ©)
 
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