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# Algebra

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Find the discriminant of the quadratic 5x^2 - 2x + 8 - 2x^2 + 6x + 2 - 2x^2 + 4x - 1.

Jun 20, 2024

### Best Answer

#2
+1230
+1

Tottenham10, you did a great job with simplifying the quadratic, but there was one tiny mistake.

The descriminant is $$b^2-4ac$$, not $$\sqrt{b^2-4ac}$$. Other than that, you're good!

So, now we...

First, let's combine all like terms. We get;

$$x^{2}+8x+9$$

Now, the decriminant is $$b^2-4ac$$ for any quadratics in the form of $$ax^2+bx+c$$

Thus, plugging in the numbers in the quadratic we have, we get

$$8^2-4(1)(9) \\ = 64- 36\\ =28$$

So 28 is our answer.

Thanks! :)

Jun 20, 2024
edited by NotThatSmart  Jun 20, 2024

### 2+0 Answers

#1
+42
-1

If we combine all the like terms, the expression turns into $$x^2+8x+9$$. The discriminant is $$\sqrt{b^2-4ac}$$, so if we just plug in the values, we get $$\sqrt{64-36}=\sqrt{28}=2\sqrt{7}$$.

Feel free to tell me if I made a mistake! :D

Jun 20, 2024
#2
+1230
+1
Best Answer

Tottenham10, you did a great job with simplifying the quadratic, but there was one tiny mistake.

The descriminant is $$b^2-4ac$$, not $$\sqrt{b^2-4ac}$$. Other than that, you're good!

So, now we...

First, let's combine all like terms. We get;

$$x^{2}+8x+9$$

Now, the decriminant is $$b^2-4ac$$ for any quadratics in the form of $$ax^2+bx+c$$

Thus, plugging in the numbers in the quadratic we have, we get

$$8^2-4(1)(9) \\ = 64- 36\\ =28$$

So 28 is our answer.

Thanks! :)

NotThatSmart Jun 20, 2024
edited by NotThatSmart  Jun 20, 2024