А. 3xВ. 63с. зD. 6х2please help ??
2 answers:
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The line is called the directrix. Here we have a vertical directrix, so a parabola sideways from usual.
Geometry is best done with squared distances. The squared distance from an arbitrary point (x,y) to the vertical line x=2 is
We equate that to the squared distance of (x,y) to the focus (-2,0):
We could call that done. A more standard form might be
Geometry is best done with squared distances. The squared distance from an arbitrary point (x,y) to the vertical line x=2 is
We equate that to the squared distance of (x,y) to the focus (-2,0):
We could call that done. A more standard form might be
Answer:
.
Step-by-step explanation:
Let represent the mass (in pounds) of that
copper alloy required, such that the final mixture would contain
copper by mass.
Consider: if pounds of that
copper alloy is mixed with
pounds that
copper alloy, what would be the mass of copper in the mixture?
- Mass of copper in
pounds of that
copper alloy:
.
- Mass of copper in
pounds of that
copper alloy:
.
Therefore, the mixture would contain of copper.
The mass of that mixture would be . The mass fraction of copper in that mixture would be:
.
This ratio is supposed to be equal to . These two pieces of equations combine to give an equation about
:
.
.
Simplify and solve for :
.
.
.
Therefore, of that
alloy would be required.