Excellent, now we're much less likely to be embarassed by talking birds. So it satisfies both of these equations and now we can type it in to verify that we got it right, although, we know that we did, so x=2 and y=-1. And you can verify that it'll work in this top equation If y = -1 and x=2, this top equation becomes -3(2) which is -6-4(-1) which would be plus 4. But this second one has already explicitly solved for y so let's use that one, so it says y = 2 times and instead of x, we now know that the x value where these two intersect, you could view it that way is going to be equal to 2, so 2 * 2 - 5 let's figure out the corresponding y value. We could take this x value to either one of these equations and solve for y. We've done, I guess you can say the hard part, we have solved for x but now we have to solve for y. And we are left with x is equal to 22 divided by 11 is 2, and the negatives cancel out. On the left hand side, we're just left with the -11x and then on the right hand side we are left with -22. Now to solve for x, we'll subtract 20 from both sides to get rid of the 20 on the left hand side. And now we can combine all the x terms so -3x-8x, that's going to be -11x and then we have -11x+20=-2. We are going to multiply -4*2x which is -8x and -4*-5 is positive 20 and thats going to equal -2. So, it's -3x and then this part right over here we have a -4, be careful, we have a -4 we want to distribute. So now we get just one equation with one unknown. So it's 4(2x-5) and all of that is going to be equal to -2. So this first blue equation would then become -3x-4 but instead of putting a y there the second constraint tells us that y needs to be equal to 2x-5. We can take this constraint, the constraint on y in terms of x and substitute it for y in this first blue equation and then solve for x. They've already made it explicitly solved for y which makes it very easy to substitute for. So, what's neat about this is that they've already solved the second equation. So this is -3x-4y=-2 and then they tell us y=2x-5. 3x-4y=-2 and y=2x-5 So let me get out my little scratch pad and let me rewrite the problem. And so this is the first exercise or the first problem that they give us. Lol.So that it's less likely that we get shown up by talking birds in the future, we've set a little bit of exercise for solving systems of equations with substitution. Additionally, if you assign specific content to your students, you can view the questions (and. However, while the students are doing the practice problems, they can use the Hint feature for missed questions to view a step-by-step solution to the problem. Or I'm just brain dead from trying to understand functions in relation to graph. We do not have currently have answer keys available for the practice problems. Wondering if anyone is feeling the same?. I feel lost in Algebra 2 because the topic progression seem to require me to hunt down the proper order of prior lessons. What I mean to say is, Algebra 1 felt like a complete package. In fact, if you clicked on the video's main page and looked at some comments, there are old requests dating back to a year stating some videos are out of order. The practice questions in Algebra 2 (particularly the ones in the 4-7th order in the list) had expressions that required knowledge from topics that are 1-2 orders ahead (Such as Log and Trigonometry). Unlike Algebra 1, where the topics were sorted in a sequential manner, the only difficult was only because there were so many new concepts to learn. There are cases where the questions were so difficult/required lessons in other topics that are at least several topics ahead. I've been into Algebra 2 for about two weeks now and am finding myself struggling at almost all the topics as some of the practice questions doesn't seem to relate to the videos within the same topic. Want to work at KA? We hire interns too!įor learning languages, we love Duolingo and Memrise.More blogs: Life at KA, School implementations, Schools blog, KA International. Official KA blog, Twitter account and Facebook page.If you have a question about a specific video, you can ask below the video itself. To report a technical problem or learn more about Khan Academy, you can visit the Help Center. To get in contact with us, see the Help Center or our Press page. This subreddit is run by Khan Academy employees, and we try to answer questions when we can, but keep in mind that it shouldn't be seen as an official way of contacting us. Khan Academy is a not-for-profit with the goal of providing a free world-class education for anyone anywhere. This is a forum for discussion about Khan Academy, and learning in general.
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