*2 values of x for perpendicular vectors

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Discussion Overview

The discussion revolves around finding the values of \( x \) for which the vectors \( \left(\frac{2x}{x-3}\right) \) and \( \left(\frac{x+1}{5}\right) \) are perpendicular. Participants explore the quadratic equation that these values satisfy and examine the validity of the solutions obtained.

Discussion Character

  • Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant claims to have derived the quadratic equation \( 2x^2 + 7x - 15 \) and identifies the solutions \( x = -5 \) and \( x = \frac{3}{2} \).
  • Another participant questions the validity of \( x = \frac{3}{2} \), stating that it does not seem to yield perpendicular vectors when substituted into the slopes.
  • A later reply suggests that \( x = \frac{3}{2} \) is indeed a proper solution, prompting further inquiry into the calculations.
  • Another participant asks for clarification on the vectors obtained when substituting \( x = \frac{3}{2} \) into the original expressions.
  • One participant acknowledges an error after further investigation.

Areas of Agreement / Disagreement

There is disagreement regarding the validity of \( x = \frac{3}{2} \) as a solution, with some participants asserting it is correct while others challenge its correctness based on their calculations.

Contextual Notes

Participants have not resolved the discrepancies in their calculations, and there are indications of missing assumptions or steps in the reasoning regarding the slopes of the vectors.

karush
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The vectors $$\left(\frac{2x}{x-3}\right)$$ and $$\left(\frac{x+1}{5}\right)$$ are $$\perp$$ for $$2$$ values of $$x $$

what is the quadratic equation which the 2 values of x satisfy

well I got $$2x^2+7x-15$$ which gives $$x=-5$$ and $$x=\frac{3}{2}$$
-5 seems to work but
$$\frac{3}{2}$$ doesn't or is there another way to do this.

thanks ahead,
 
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Re: 2 values of x for perpendicular vectors

karush said:
The vectors $$\left(\frac{2x}{x-3}\right)$$ and $$\left(\frac{x+1}{5}\right)$$ are $$\perp$$ for $$2$$ values of $$x $$

what is the quadratic equation which the 2 values of x satisfy

well I got $$2x^2+7x-15$$ which gives $$x=-5$$ and $$x=\frac{3}{2}$$
-5 seems to work but
$$\frac{3}{2}$$ doesn't or is there another way to do this.

thanks ahead,

Hi karush! :)

What is the reason you think $x=\frac 3 2$ does not work?
It is a proper solution.
 
Re: 2 values of x for perpendicular vectors

when I plugged $$\frac{3}{2}$$ in the slopes didn't seem $$\perp$$
 
Re: 2 values of x for perpendicular vectors

karush said:
when I plugged $$\frac{3}{2}$$ in the slopes didn't seem $$\perp$$

Well... which vectors do you get if you plug it in?
 
Re: 2 values of x for perpendicular vectors

OK found my error...
 

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