![]() And then they either areĪbout to make a mistake, this is actually algebraically valid. This left hand expression, say that's going to be x plus three times x plus one, and then that's going toīe equal to negative one. That add up to four and whose product is three. See something like this, let me rewrite it. You'll sometimes see people use, especially when they But if can't make these things disappear, this strategy that I've just outlined is not going to be a productive one. But if you have an x term like this and it doesn't cancel out somehow, you know, if there was anotherįour x on the other side, then you could subtractįour x from both sides, and they would disappear. Then this strategy would have worked assuming that there are some solutions. In fact, it would have worked if you did not have ![]() Now, there's some cases in which this strategy would have worked. You still don't know what x is, and it's really not clear what to do with this algebraically. Of negative four x minus four, but this still doesn't help you. And you could get something like this, you would get x is equal to plus or minus the square root The plus of minus of one side to make sure you're Square root of x squared is equal to, and you could try to take And now, someone might say, if I take the square root of both sides, I could get, I'll just write that down. And then what happens? On the left hand side, you do indeed isolate the x squared, and on the right hand side, you get negative four x minus four. Isolate that x squared by subtracting four x from both sides and subtracting three from both sides. So you could imagine, let me just rewrite it. People will try to go for is to isolate the x squared first. So just willy nilly, taking the square root ofīoth sides of a quadratic is not going to be too helpful. Isolate the x over here? You've pretty quickly hit a dead end. But even if this wasĪ positive value here, how do you simplify or how do you somehow Even if this wasn't a negative one here, that's the most obvious problem. Plus four x plus three is equal to the square The square root of both sides? And if you did that, you would get the square root of x squared So one strategy that people might try is, well, I have something squared, why don't I just try to take I have something on both sides of an equal sign. Why is it a quadratic equation? Well, it's a quadratic because it has this secondĭegree term right over here and it's an equation because You can clearly see the solutions x = -1 and x = 5.- In this video, we're gonna talk aboutĪ few of the pitfalls that someone might encounter while they're trying to solve a quadratic equation like this. If you're interested, you can download the accompanying Excel file.Įxplanation: the points where the curve intersects the horizontal line represent the solutions to the quadratic equation for the given y-value. Create an XY scatter chart and add a horizontal line (y = 24.5) to the chart. Populate column A with multiple x-values and find their corresponding y-values by dragging the formula in cell B2 down.ġ1. Let's visualize the solutions of y = 3x 2 - 12x + 9.5 = 24.5.ġ0. In this case, set 'To value' to 0.īonus! Improve your understanding of quadratic equations by visualizing the solutions on a chart. To find the roots, set y = 0 and solve the quadratic equation 3x 2 - 12x + 9.5 = 0. For example, enter the value 0 into cell A2 and repeat steps 5 to 9. ![]() Excel finds the other solution (x = -1) if you start with an x-value closer to -1. Click in the 'By changing cell' box and select cell A2. Click in the 'To value' box and type 24.5Ĩ. On the Data tab, in the Forecast group, click What-If Analysis.ħ. ![]() You can use Excel's Goal Seek feature to obtain the exact same result. But what if we want to know x for any given y? For example, y = 24.5. ![]()
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