MHB Show that the area of the rectangle is....

  • Thread starter Thread starter mathlearn
  • Start date Start date
  • Tags Tags
    Area Rectangle
AI Thread Summary
The discussion centers on calculating the area of a rectangle with length x+1 and breadth x, where x is defined as -1±√11. Participants clarify that only the positive root, x=√11-1, is valid since dimensions cannot be negative. The area is ultimately expressed as (√11)(√11) - (√11), simplifying to 11 - √11. There is confusion regarding the multiplication of the area expression by -1, which is addressed in the conversation. The final area calculation is confirmed as correct, emphasizing the importance of using the appropriate value for x.
mathlearn
Messages
331
Reaction score
0
There's a rectangle which the length is x+1 and the breadth is x.

X is $$-1\pm\sqrt{11}$$

Show that the area is $$11-\sqrt{11}$$

The workings I have done for far are below.

$$(-1\pm \sqrt{11})*(-1 \pm \sqrt{11} +1) $$

$$(-1\pm \sqrt{11})*( \pm \sqrt{11} ) $$

$$(-1\pm \sqrt{11})*( \pm \sqrt{11} ) $$

$$(-1\pm \sqrt{11})*( \pm \sqrt{11} ) $$

Where have I done wrong ? And the square root of the solution of the area you are asked to show is a negative. A comment here would be appreciated.

Many thanks :)
 
Mathematics news on Phys.org
Measures cannot be negative, so we must have:

$$x=\sqrt{11}-1$$

And so:

$$x+1=\sqrt{11}$$

So, what is the area?
 
MarkFL said:
Measures cannot be negative, so we must have:

$$x=\sqrt{11}-1$$

And so:

$$x+1=\sqrt{11}$$

So, what is the area?

$$(-1+ \sqrt{11})*( + \sqrt{11} ) $$

$$ - \sqrt{11}+ 11 $$

Correct? :)
 
Why would you multiply the expression representing the area by -1?

edit: I see you edited your post. :D
 
MarkFL said:
Why would you multiply the expression representing the area by -1?

edit: I see you edited your post. :D

(Party)(Party)(Happy) Thank you very much MarkFL
 
Suppose ,instead of the usual x,y coordinate system with an I basis vector along the x -axis and a corresponding j basis vector along the y-axis we instead have a different pair of basis vectors ,call them e and f along their respective axes. I have seen that this is an important subject in maths My question is what physical applications does such a model apply to? I am asking here because I have devoted quite a lot of time in the past to understanding convectors and the dual...
Fermat's Last Theorem has long been one of the most famous mathematical problems, and is now one of the most famous theorems. It simply states that the equation $$ a^n+b^n=c^n $$ has no solutions with positive integers if ##n>2.## It was named after Pierre de Fermat (1607-1665). The problem itself stems from the book Arithmetica by Diophantus of Alexandria. It gained popularity because Fermat noted in his copy "Cubum autem in duos cubos, aut quadratoquadratum in duos quadratoquadratos, et...
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
Back
Top