Rmember (a/b)/(c/d)=(a/b)(d/c)=(ad)/(bc)this is just alot of busy work
find f+g first then find f-g
f+g=(x-4)/(x+9)+(x-9)/(x+4)
make denomenator the same
multiply left one by (x+4)/(x+4) and right one by (x+9)/(x+9)
[(x-4)(x+4)]/[(x+9)(x+4)]+[(x-9)(x+9)]/[(x+9)(x+4)]
[x²-16]/[(x+9)(x+4)]+[x²-81]/[(x+9)(x+4)]
[x²+x²-16-81]/[(x+9)(x+4)]
[2x²-97]/[(x+9)(x+4)]
now f-g
[x²-16]/[(x+9)(x+4)]-[x²-81]/[(x+9)(x+4)]
[x²-x²-16+81]/[(x+9)(x+4)]
[65]/[(x+9)(x+4)]
now we got
invert and multiply
2nd option
In the figure we have the graphic of this equation. So, the vertex is the maximum of this function. This point means that the maximum <span>daily profit from soccer balls is:
</span>
<span>
And this happens when the </span><span>selling price of each soccer ball is:
</span>
<span>
So if you want to get the best daily profit, this is the price you must sell each soccer ball.</span>
<span><span>(<span><span>12</span><span>(<span>3+7</span>)</span></span>)</span><span>(3.5)</span></span><span>=<span><span><span>12</span><span>(<span>3+7</span>)</span></span><span>(3.5)</span></span></span><span>=<span><span><span>12</span><span>(<span>3+7</span>)</span></span><span>(3.5)</span></span></span><span>=<span><span>(<span><span>12</span><span>(10)</span></span>)</span><span>(3.5)</span></span></span><span>=<span><span>(5)</span><span>(3.5)</span></span></span><span>=17.5
</span>