Math 9 Midterm Review: Subracting Polynomials

When our class first learned how to subtract polynomials, I was away. When it came to the test, I thought i had understood how to do it, but obviously not. On it, I didn’t do good. Looking back on the quiz, I notice the mistakes I had made.

For example, there was (2x-6)+(x+4)-(4x+1). I wrote down what i thought was an easier way to look at it:(2x-6)+(x+4)+(4x-1), and that I didn’t combine x with 4x and 2x. In total, the math I had done was (2x+4x)+(-6-1)+x. Making those mistakes, I came up with the answer 6x-3+x. Looking at it now, I should have simplified the question to (2x-6)+(x+4)+(-4x-1), that way I can get the correct answer of -x-3. The math I did was (2x+x-4x)+(-6+4-1).

Another example is (-5-3x*-2)-(4x+x*-8). Out of the 4 questions in this section, this was the hardest one, even doing the second time. At first, I got it wrong while correcting it, but I used a math calculator app and I figured out where I went wrong. During the quiz, I simplified it to (-5-3x*-2)+(4x-x*+8), and got the answer of -x-4x*+6. My math was (-3x*-x*)+(-5x+4x)+(-2+8) I should have simplified it to (-5x-3x*-2)+(-4x-2x+8), and get the answer -4x*-9x+6. The math should have been (-3x*-x*)+(-5x-4x)+(-2+8) When correcting it the first time, i accidentally did 3x*-x* instead of -3x*-x*, so i got 2x* instead of -4x*, which confused me, but i got the right answer in the end.

(Note: I am using * as a symbol for squared)




Categories: Math 9

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