1 00:00:00,000 --> 00:00:00,660 2 00:00:00,660 --> 00:00:04,750 We're asked to simplify 8 plus 5 times 4 minus, and then in 3 00:00:04,750 --> 00:00:09,010 parentheses, 6 plus 10 divided by 2 plus 44. 4 00:00:09,010 --> 00:00:12,120 Whenever you see some type of crazy expression like this 5 00:00:12,120 --> 00:00:15,360 where you have parentheses and addition and subtraction and 6 00:00:15,360 --> 00:00:17,760 division, you always want to keep the order of 7 00:00:17,760 --> 00:00:19,000 operations in mind. 8 00:00:19,000 --> 00:00:20,970 Let me write them down over here. 9 00:00:20,970 --> 00:00:23,420 So when you're doing order of operations, or really when 10 00:00:23,420 --> 00:00:24,820 you're evaluating any expression, you should have 11 00:00:24,820 --> 00:00:29,520 this in the front of your brain that the top priority 12 00:00:29,520 --> 00:00:30,770 goes to parentheses. 13 00:00:30,770 --> 00:00:37,850 14 00:00:37,850 --> 00:00:40,060 And those are these little brackets over here, or however 15 00:00:40,060 --> 00:00:40,670 you want to call them. 16 00:00:40,670 --> 00:00:42,320 Those are the parentheses right there. 17 00:00:42,320 --> 00:00:44,030 That gets top priority. 18 00:00:44,030 --> 00:00:46,120 Then after that, you want to worry about exponents. 19 00:00:46,120 --> 00:00:48,240 There are no exponents in this expression, but I'll just 20 00:00:48,240 --> 00:00:52,150 write it down just for future reference: exponents. 21 00:00:52,150 --> 00:00:55,000 One way I like to think about it is parentheses always takes 22 00:00:55,000 --> 00:00:58,730 top priority, but then after that, we go in descending 23 00:00:58,730 --> 00:01:01,610 order, or I guess we should say in-- well, yeah, in 24 00:01:01,610 --> 00:01:05,400 descending order of how fast that computation is. 25 00:01:05,400 --> 00:01:07,520 When I say fast, how fast it grows. 26 00:01:07,520 --> 00:01:09,800 When I take something to an exponent, when I'm taking 27 00:01:09,800 --> 00:01:13,270 something to a power, it grows really fast. Then it grows a 28 00:01:13,270 --> 00:01:15,730 little bit slower or shrinks a little bit slower if I 29 00:01:15,730 --> 00:01:17,760 multiply or divide, so that comes 30 00:01:17,760 --> 00:01:21,800 next: multiply or divide. 31 00:01:21,800 --> 00:01:24,910 Multiplication and division comes next, and then last of 32 00:01:24,910 --> 00:01:27,550 all comes addition and subtraction. 33 00:01:27,550 --> 00:01:29,950 So these are kind of the slowest operations. 34 00:01:29,950 --> 00:01:31,450 This is a little bit faster. 35 00:01:31,450 --> 00:01:33,610 This is the fastest operation. 36 00:01:33,610 --> 00:01:35,290 And then the parentheses, just no matter 37 00:01:35,290 --> 00:01:36,980 what, always take priority. 38 00:01:36,980 --> 00:01:38,180 So let's apply it over here. 39 00:01:38,180 --> 00:01:40,290 Let me rewrite this whole expression. 40 00:01:40,290 --> 00:01:47,960 So it's 8 plus 5 times 4 minus, in parentheses, 6 plus 41 00:01:47,960 --> 00:01:53,150 10 divided by 2 plus 44. 42 00:01:53,150 --> 00:01:55,730 So we're going to want to do the parentheses first. We have 43 00:01:55,730 --> 00:02:00,050 parentheses there and there. 44 00:02:00,050 --> 00:02:02,170 Now this parentheses is pretty straightforward. 45 00:02:02,170 --> 00:02:05,120 Well, inside the parentheses is already evaluated, so we 46 00:02:05,120 --> 00:02:08,009 could really just view this as 5 times 4. 47 00:02:08,009 --> 00:02:11,000 So let's just evaluate that right from the get go. 48 00:02:11,000 --> 00:02:14,935 So this is going to result in 8 plus-- and really, when 49 00:02:14,935 --> 00:02:16,650 you're evaluating the parentheses, if your evaluate 50 00:02:16,650 --> 00:02:18,980 this parentheses, you literally just get 5, and you 51 00:02:18,980 --> 00:02:21,070 evaluate that parentheses, you literally just get 4, and then 52 00:02:21,070 --> 00:02:22,930 they're next to each other, so you multiply them. 53 00:02:22,930 --> 00:02:28,170 So 5 times 4 is 20 minus-- let me stay 54 00:02:28,170 --> 00:02:29,960 consistent with the colors. 55 00:02:29,960 --> 00:02:34,290 Now let me write the next parenthesis right there, and 56 00:02:34,290 --> 00:02:38,050 then inside of it, we'd evaluate this first. Let me 57 00:02:38,050 --> 00:02:40,080 close the parenthesis right there. 58 00:02:40,080 --> 00:02:43,280 And then we have plus 44. 59 00:02:43,280 --> 00:02:46,250 So what is this thing right here evaluate to, this thing 60 00:02:46,250 --> 00:02:47,800 inside the parentheses? 61 00:02:47,800 --> 00:02:49,170 Well, you might be tempted to say, well, let me 62 00:02:49,170 --> 00:02:50,160 just go left to right. 63 00:02:50,160 --> 00:02:53,770 6 plus 10 is 16 and then divide by 2 and 64 00:02:53,770 --> 00:02:54,780 you would get 8. 65 00:02:54,780 --> 00:02:57,080 But remember: order of operations. 66 00:02:57,080 --> 00:03:01,760 Division takes priority over addition, so you actually want 67 00:03:01,760 --> 00:03:04,850 to do the division first, and we could actually write it 68 00:03:04,850 --> 00:03:05,790 here like this. 69 00:03:05,790 --> 00:03:07,960 You could imagine putting some more parentheses. 70 00:03:07,960 --> 00:03:09,790 Let me do it in that same purple. 71 00:03:09,790 --> 00:03:13,200 You could imagine putting some more parentheses right here to 72 00:03:13,200 --> 00:03:16,110 really emphasize the fact that you're going to do the 73 00:03:16,110 --> 00:03:17,760 division first. 74 00:03:17,760 --> 00:03:24,740 So 10 divided by 2 is 5, so this will result in 6, plus 10 75 00:03:24,740 --> 00:03:27,560 divided by 2, is 5. 76 00:03:27,560 --> 00:03:28,730 6 plus 5. 77 00:03:28,730 --> 00:03:32,230 Well, we still have to evaluate this parentheses, so 78 00:03:32,230 --> 00:03:34,600 this results-- what's 6 plus 5? 79 00:03:34,600 --> 00:03:36,050 Well, that's 11. 80 00:03:36,050 --> 00:03:38,630 So we're left with the 20-- let me 81 00:03:38,630 --> 00:03:39,630 write it all down again. 82 00:03:39,630 --> 00:03:44,050 We're left with 8 plus 20 minus 6 plus 5, 83 00:03:44,050 --> 00:03:47,000 which is 11, plus 44. 84 00:03:47,000 --> 00:03:50,820 And now that we have everything at this level of 85 00:03:50,820 --> 00:03:53,580 operations, we can just go left to right. 86 00:03:53,580 --> 00:03:58,770 So 8 plus 20 is 28, so you can view this as 28 87 00:03:58,770 --> 00:04:01,890 minus 11 plus 44. 88 00:04:01,890 --> 00:04:06,030 28 minus 11-- 28 minus 10 would be 18, so this 89 00:04:06,030 --> 00:04:07,386 is going to be 17. 90 00:04:07,386 --> 00:04:10,630 It's going to be 17 plus 44. 91 00:04:10,630 --> 00:04:16,209 And then 17 plus 44-- I'll scroll down a little bit. 92 00:04:16,209 --> 00:04:21,160 7 plus 44 would be 51, so this is going to be 61. 93 00:04:21,160 --> 00:04:24,940 So this is going to be equal to 61. 94 00:04:24,940 --> 00:04:26,460 And we're done! 95 00:04:26,460 --> 00:04:26,599