I came across the following on pg. 33 of the OG Quantitative

Question

I came across the following on pg. 33 of the OG Quantitative Review, and I believe it is an error.

Solving Equations by Factoring example:

x^3 - 2x^2 + X + 5(x-1)^2 = 0
x (x^2+2x+1)  + 5(x-1)^2 = 0
x (x-1)^2  + 5(x-1)^2 = 0
(x+5) (x-1)^2 = 0
x + 5 = 0 or (x-1)^2 = 0
x = -5 or x = 1.

I don't understand the high-lighted terms. Doesn't (x-1)^2 equal  x^2 - 2x +1 , or am I missing a math concept?

sondenso · Answer

Typo, OG writer is human too!

WSR · Answer

Thanks for the response. I just needed to confirm that to ensure I understood the concept! :-D

alpha_plus_gamma · Answer

Hope the same human will not set a Q for me :lol:

sondenso · Answer

I saw that reasoning has only error in typo, b/c the correct solution is x=-5 andx=1 is correct. So I think error is typing! :lol:

ritula · Answer

the typing error is only in x^2+2x+1. it should bew -2x . rest solution is ok

WSR · Answer

What is frustrating is that the guide is littered with careless mistakes. If someone is using this to brush up on basic math skills, then it becomes confusing.

Another error I found this morning:

0-2/2-(-2) = -2/4 = 1/2.

The correct answer is -1/2, not 1/2. There is no excuse for such careless mistakes in a reference document, IMHO.

jallenmorris · Answer

How is this answer -1/2 or even 1/2?

I think you need to use the math formula for this to make sense and be read the way you mean it.

It appears at first glance that you are writing the following:

0-\frac{2}{2}-(-2)} = \frac{-2}{4} = \frac{1}{2} , which would clearly be -1 - -2, or +1. 
Is this the way it is intended?

0-\frac{2}{2-(-2)} = \frac{-2}{4} = \frac{1}{2}

And yeah, you're right, it should be  \frac{-1}{2}

jallenmorris · Answer

I think the error could be in either part

x^2+2x+1 = (x+1)^2  and  x^2-2x+1 = (x-1)^2

As long as one is changed, such as instead of  +2x , you have  -2x , then the rest of the explanation is correct. If  +2x  is correct, then the  (x-1)^2  should have been  (x+1)^2

I came across the following on pg. 33 of the OG Quantitative

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