Let
x----------------> <span>width of the margin
we know that
[Area </span><span>printed matter]=140
</span>[Area printed matter]=[(14-2x)*(18-2x)]
then
[(14-2x)*(18-2x)]=140--------> (252-28x-36x+4x²)=140
(252-64x+4x²)=140----------> 4x²-64x+112=0
using a graph tool---------> <span>I solve the quadratic equation
see the attached figure
x1=2
x2=14----------> is not solution
the answer is
the margin should be 2 cm</span>
The <em><u>correct answer</u></em> is:
non-extraneous
Explanation:
An extraneous solution is one that we arrive at that will not work in the equation. For rational equations such as we have, extraneous solutions are ones that will cause the denominator to be 0. For ours, that would mean x=-5.
The equation we have is:
![\frac{3}{x+5}+\frac{1}{5}=\frac{2}{x+5}](https://tex.z-dn.net/?f=%5Cfrac%7B3%7D%7Bx%2B5%7D%2B%5Cfrac%7B1%7D%7B5%7D%3D%5Cfrac%7B2%7D%7Bx%2B5%7D)
We will multiply everything by (x+5) in order to get that off the bottom of the fractions:
![\frac{3}{x+5}\times (x+5)+\frac{1}{5}\times (x+5)=\frac{2}{x+5}\times (x+5) \\ \\3+\frac{x+5}{5}=2](https://tex.z-dn.net/?f=%5Cfrac%7B3%7D%7Bx%2B5%7D%5Ctimes%20%28x%2B5%29%2B%5Cfrac%7B1%7D%7B5%7D%5Ctimes%20%28x%2B5%29%3D%5Cfrac%7B2%7D%7Bx%2B5%7D%5Ctimes%20%28x%2B5%29%0A%5C%5C%0A%5C%5C3%2B%5Cfrac%7Bx%2B5%7D%7B5%7D%3D2)
Multiply all terms by 5 to eliminate the fraction:
![3\times 5+\frac{x+5}{5}\times 5=2\times 5 \\ \\15+x+5=10](https://tex.z-dn.net/?f=3%5Ctimes%205%2B%5Cfrac%7Bx%2B5%7D%7B5%7D%5Ctimes%205%3D2%5Ctimes%205%0A%5C%5C%0A%5C%5C15%2Bx%2B5%3D10)
Combine like terms:
20+x = 10
Subtract 20 from each side:
20+x-20 = 10-20
x = -10
Since this is not -5, this is not an extraneous solution.
<ADB = 90 degrees
hope it helps
Answer:
78 units squared
Step-by-step explanation:
Answer:
(n-5)(n+5)
Step-by-step explanation:
n^2-25
(n-5)(n+5)