Algebra question/geometry solving the system 3x + 2y = 21, (7 - x)² + y² = 2².
what does this mean ?
How to get the answer  (7−4/√13,6/√13)
 A: It means to find the numerical values for x and y that make both equations true at the same time.  There are many ways to do so.  For example, in the first equation you might isolate for $x$, then substitute the expression you get for $x$ into the second equation.  This will give you a number for $y$, which when substituted into either of the original equations will yield a number for $x$.
Geometrically, the two equations describe curves in 2D space.  The points where they are both true is where the two curves intersect.  These intersection points are the points $(x,y)$ you will find by the above procedure - the numbers where the equations are both true.
A: This means that you have a linear graph 3x+2y=21 and a circle, with origin at (7,0) and a radius of 2. To solve this system, you need to find the intersection point of these 2 graphs. 
Edit:
My algebraic solution:
$3x+2y=21\\
2y=21-3x\\
y=\frac{21-3x}{2}\\
(7-x)^2+\frac{9}{4} \cdot (7-x)^2=4\\
\frac{13}{4} \cdot (7-x)^2=4\\
(7-x)^2=\frac{16}{13}\\
x-7=\pm \frac{4}{\sqrt{13}}\\
x=7 \pm \frac{4}{\sqrt{13}}$
