Example 2: Adding polynomials | Algebra I | Khan Academy

Example 2: Adding polynomials | Algebra I | Khan Academy


We’re asked to simplify 5x
squared plus 8x minus 3 plus 2x squared minus 7x plus 13x. So really, all we have to do
is we have to combine like terms– terms that have x raised
to the same power. And the first thing we can do,
we can actually get rid of these parentheses right here,
because we have this whole expression, and then we’re
adding it to this whole expression. The parentheses really don’t
change our order of operations here. So let me just rewrite it once
without the parentheses. So we have 5x squared plus 8x
minus 3 plus 2x squared. If this was a minus then we’d
have to distribute the negative sign, but it’s not. So plus 2x squared minus
7x plus 13x. Now let’s just look at the
different terms that have different degrees of x. Let’s start with the x squared
terms. So you have a 5x squared term here and you have a
2x squared term right there. So 5 of something plus 2 of that
same something is going to be 7 of that something. So that’s going to
be 7x squared. And then let’s look at
the x terms here. So we have an 8x right there. We have a minus 7x. And then we have a plus 13x. So if you have 8 of something
minus 7 of something, you’re just going to have 1
of that something. And then if you add 14 of
that something more, you’re going to 15. So this is going
to be plus 15x. 8x minus 7x– oh, sorry. You’re going to have 14x. 8 minus 7 is 1 plus 13 is 14. Plus 14x. That’s these three terms.
8x minus 7x plus 13x. And then finally, you have a
negative 3– or minus 3, depending on how you
want to view it. And that’s the only
constant term. You could say it’s x
times x to the 0. But it’s a constant term. It’s not be multiplied by x. And that’s the only one
there, so minus 3. And we’ve simplified it
as far as we can go. We are done.

29 thoughts on “Example 2: Adding polynomials | Algebra I | Khan Academy

  • May 16, 2011 at 11:30 pm
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    can you be my teacher?? forever?? please

    Reply
  • November 16, 2011 at 3:40 pm
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    word.

    Reply
  • December 3, 2011 at 9:37 am
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    got a score 44/50 on my quiz because of this! Thanks Sal!

    Reply
  • December 15, 2011 at 1:37 am
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    I got a 99 on my Math Exam bc of this!! Thanks!

    Reply
  • January 26, 2012 at 6:15 pm
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    Thanks Sal Your The BOMMB yeah 🙂 hehehehe pickles

    Reply
  • January 26, 2012 at 6:16 pm
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    @italianstallion929 Good Job random person

    Reply
  • January 26, 2012 at 6:16 pm
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    @godzilla8345 okay then lul

    Reply
  • January 26, 2012 at 6:17 pm
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    @prettiecake lul its the new lol yeah 😉

    Reply
  • February 6, 2012 at 2:34 am
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    Thank you!! This really helped me a lot because I was absent from school the day we learned this.

    Reply
  • May 31, 2012 at 6:19 pm
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    He already is 🙂 u can view his vids at any time

    Reply
  • March 11, 2013 at 2:00 am
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    Omg Your awesome. But what did you do to the 13x? I'm confused

    Reply
  • March 19, 2013 at 5:39 pm
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    tylers gay

    Reply
  • October 1, 2013 at 11:09 pm
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    THANKS THAT HELPED!!

    Reply
  • June 5, 2014 at 6:57 pm
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    Thank you so much! 
    I have been struggling in school because I couldn't understand what I had to do but after I had watched this video it all made sense!

    Reply
  • October 19, 2014 at 2:41 am
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    Thank you so much, Its really help in my assignment! 

    Reply
  • March 9, 2016 at 12:05 am
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    Thanks for refreshing my mind. I came to class late and had no idea what the teacher was lecturing about. She talks pretty fast. Simple stuff.

    Reply
  • January 10, 2017 at 9:33 pm
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    thanks. I needed to refresh my skills. also do you notice there's so many views but so few comments?

    Reply
  • February 6, 2017 at 1:53 am
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    thx khan academy

    Reply
  • March 10, 2017 at 5:49 am
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    thanks, it really helps my final exam! and it is easy to understand

    Reply
  • September 24, 2017 at 8:14 pm
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    if only my algebra2/trig teacher was good at explaining as you and i go to a private school for gods sake XD

    Reply
  • October 16, 2017 at 2:56 pm
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    Thank you so much

    Reply
  • November 30, 2017 at 10:15 am
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    omg it really helps me! and oh gosh my heart is pumping hard, the our exam will be like forever!

    Reply
  • December 6, 2017 at 12:48 am
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    Dude these vids help me Soo much my teacher sucks so these are a lifesaver
    Thank yiu

    Reply
  • September 9, 2018 at 9:29 pm
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    Oh my gosh thank you! My algebra 1 teacher talks too fast, and this method is even more easy than she taught me!

    Reply
  • October 8, 2018 at 7:45 pm
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    Wow, So you just combine like terms! 😐

    Reply
  • November 13, 2018 at 12:39 pm
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    "This something" and "that something" helped me so much lolz

    Reply
  • December 13, 2018 at 6:16 pm
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    How do i know which sign to put?

    Reply
  • March 18, 2019 at 3:38 pm
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    Yoo this is so helpful. But when he said oh sorry its 14x am not sure cuz it is 15x

    Reply
  • March 20, 2019 at 10:59 am
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    8+7=15 Boiiiiiiii😂😂😂😂😂😂😂😂

    Reply

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