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Jan
22
comment factor the following expression $25x^2 +5xy -6y^2$
Imagine that - someone who actually knows how to teach!
Jan
22
comment factor the following expression $25x^2 +5xy -6y^2$
You found the factor pair of $ac = -150$ that sums to $b= 5$. Your comparison is ludicrous, and pedagogy deplorable.
Jan
22
comment factor the following expression $25x^2 +5xy -6y^2$
Yes, but how did you "choose" $15-10$? Why not $9-4$ or $1+4$? To a student, your choice just looks like a guess, whence "divine".
Jan
22
comment factor the following expression $25x^2 +5xy -6y^2$
It's not clear to me how you divined that $5 = 15 - 10$ (and not some other sum)
Jan
22
comment factor the following expression $25x^2 +5xy -6y^2$
Here's the general method: adamlchan.com/math/topics/ac_factoring/index.php
Jan
22
comment factor the following expression $25x^2 +5xy -6y^2$
@Joffan, that's almost useless. We need to find the factors of $ac = -150$.
Jan
22
answered Order of Inverse Operations
Jan
16
comment Help understanding what is asked of me
That "wedge" notation coincides with the little that I know about fuzzy logic: ($A$ and $B$), for $ 0 \leq A, B, \leq 1$ is the minimum of $A,B$.
Jan
16
comment Help understanding what is asked of me
Ducksauce, I'm almost certain it's in your book somewhere. What text are you using? (Or can you upload a scan of your notes?)
Jan
16
comment All matrices which commute with all $2\times 2$ matrices
@USB - for the sake of argument, how do you know that "this answer is correct"?
Jan
15
comment The Sum Of Sets Or Intervals
You're ignoring the context. $A$ and $B$ must be sets where addition ($+$) makes sense. So then the addition on the L.H.S. is really a new type, defined by adding (using the addition of $A,B$) elements of $A,B$.
Jan
15
comment Breaking symmetries
The link in the penultimate paragraph is dead ("inaccessible")...
Jan
14
comment Finding a limit algebraically
Lots of spoon-feeding going on in these answers! And yet nobody took the time to demonstrate the manipulation of the L.H.S...
Jan
12
comment Combinatorics: Prove the number of matches in a Singles Tournament
How is it obvious?
Jan
8
reviewed Approve Why the answer to $\log(x+3)+\log(x+2)\geq \log 12$ different from that of $\log(x^2+5x+6)\geq \log12$?
Jan
7
comment Determining the points of a rotated square.
First line here: en.wikipedia.org/wiki/Rotation_matrix
Dec
10
comment What does this summation notation denote?
Well it's explained right there in the wikipedia page! The "sum" is really more like a successive adding, then subtracting, then adding, then...
Dec
10
comment Evaluating $\frac{d}{dx}\int_{7-2x}^3 \frac{u^3}{1+u^2}du$
I'd switch the limits and (thereby) the sign...
Dec
10
comment What is the difference between $\{1, 2\}\cup\{3\}$ and $\{1, 2, 3\}$?
Right, and we "can" say $1=5$ or omit the differential in an integral, but we'd better keep it conventional for the elementary stuff.
Dec
10
comment What is the difference between $\{1, 2\}\cup\{3\}$ and $\{1, 2, 3\}$?
0 is certainly not the appropriate symbol