Matrix addition and subtraction | Matrices | Precalculus | Khan Academy

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Precalculus on Khan Academy: You may think that precalculus is simply the course you take before calculus. You would be right, of course, but that definition doesn't mean anything unless you have some knowledge of what calculus is. Let's keep it simple, shall we? Calculus is a conceptual framework which provides systematic techniques for solving problems. These problems are appropriately applicable to analytic geometry and algebra. Therefore....precalculus gives you the background for the mathematical concepts, problems, issues and techniques that appear in calculus, including trigonometry, functions, complex numbers, vectors, matrices, and others. There you have it ladies and gentlemen....an introduction to precalculus!

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[Peter_]

One thing I really like about Sal is his incredible ability to understand his students - he knows EXACTLY when people would normally start asking themselves questions and feeling slightly insecure about certain topics, and then he instantly gives an example on that.

[McGavel]

Cool point about how matrix operations are undefined if the matrices are of different dimensions. Thanks for the info.

[withotro]

Great video 👍. It was good to find out that different dimensions will result in undefined.

[The]

WTF school, teach me shit in 67 mins i can learn in 5 on youtube?!?

[robyn]

excellent education . its so brilliantly explained and easy to understand

[jamesjiao]

Ahha.. that's the problem.. which row? which column? :). That's why it's defined. You could insert the row/column *anywhere*, hence making the result inconsistent.

[jamesjiao]

Will you be covering shearing and reflection?

[tofitamorgan]

would you please make a video for determinants and matrices together?

[kamalasharma]

Can we subtract 3 matrices at a time or first we have to subtract two of them and then the 3rd one with the result of the subtraction of first two....will the answers be same on both the type????

[vrotherbrotherhood]

so we cant add or subtract matrices with diff dimensions

[rashimsalehrahman]

5:14 yeah, he called that a 0, not 6.
helpful videos tho.

This might sound like a stupid question, but why wouldn't the numbers in the undefined rows or columns just be set to zero?

[rigille]

but subtraction isn't commutative, x-y = y-x is only true when x = y. Did you mean "like addition"?

[ogeidnomar]

What would happen if the 2x2 matrix had placeholder 1s in order to satisfy the 3x2 matrix operation?

[hamamath]

hi please can you help me for this example integral(x^x dx)

[Isiloron]

You forgot to mention that matrix subtraction is not commutative just like regular subtraction.

[ClashOfNinja]

not so much gave up, just found it to be pointless. If there was a convenient, sensible, reasonable, standard way to define it, they would, but as it stands, it isn't a problem.

[danielcat]

What if you just used 0 place holders for the matrix with different dimensions? That would be logical to me.

[pompasduris]

at 0:04 seconds, is "choosen" a word? 😆

[TheHeapOverflow]

For better quality perhaps? Some of the old videos were hard to see.