lauren1998
New member
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- Mar 6, 2012
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I am in Algebra 1 and do not understand how to do this math...please help!
Thanks,
Lauren
Thanks,
Lauren
Quadratic Equations: Differences of Squares.
- Thread starter lauren1998
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Iceycold12
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- Feb 24, 2012
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Okay I'm not really the best to answer here but I'm in Algebra I as well, and I understand this so here is some help, I'd wait for the pros to come first though. They are like gods of Math 
Say you have x^2-25, you need to find the factors of -25 that add up to 0. -5 + 5 = 0 doesn't it? So you set up the answer like this: (x+5)(x-5) When you FOIL that you get x^2-25.
Say you have a number greater than 1 behind x. For example, 49x^2-81. Same method as the above but in the final two binomials you need numbers that FOIL into the 49x^2.
I. Find the factors of -81 that add up to 0.
II. 9 & -9.
III. What two numbers give 49? 7x7.
IV. Write the end result like this: (7x+9)(7x-9)
V. Foil that and you get 7x*7x = 49x^2 9*-9 = -81.
VI. End result: 49x^2-81.
Again, I'd wait for the pros.
Say you have x^2-25, you need to find the factors of -25 that add up to 0. -5 + 5 = 0 doesn't it? So you set up the answer like this: (x+5)(x-5) When you FOIL that you get x^2-25.
Say you have a number greater than 1 behind x. For example, 49x^2-81. Same method as the above but in the final two binomials you need numbers that FOIL into the 49x^2.
I. Find the factors of -81 that add up to 0.
II. 9 & -9.
III. What two numbers give 49? 7x7.
IV. Write the end result like this: (7x+9)(7x-9)
V. Foil that and you get 7x*7x = 49x^2 9*-9 = -81.
VI. End result: 49x^2-81.
Again, I'd wait for the pros.