The problem is to find the values of $x$ and $y$ given two equations: $\frac{2}{x} + \frac{3}{3y} = \frac{9}{xy}$ and $\frac{4}{x} + \frac{9}{y} = \frac{21}{xy}$, where $x \neq 0$ and $y \neq 0$.

AlgebraSystems of EquationsLinear EquationsSolving EquationsRational Equations
2025/3/13

1. Problem Description

The problem is to find the values of xx and yy given two equations:
2x+33y=9xy\frac{2}{x} + \frac{3}{3y} = \frac{9}{xy} and 4x+9y=21xy\frac{4}{x} + \frac{9}{y} = \frac{21}{xy}, where x0x \neq 0 and y0y \neq 0.

2. Solution Steps

First, simplify the equations:
2x+1y=9xy\frac{2}{x} + \frac{1}{y} = \frac{9}{xy} (Equation 1)
4x+9y=21xy\frac{4}{x} + \frac{9}{y} = \frac{21}{xy} (Equation 2)
Multiply both sides of Equation 1 by xyxy:
xy(2x+1y)=xy(9xy)xy (\frac{2}{x} + \frac{1}{y}) = xy (\frac{9}{xy})
2y+x=92y + x = 9 (Equation 3)
Multiply both sides of Equation 2 by xyxy:
xy(4x+9y)=xy(21xy)xy (\frac{4}{x} + \frac{9}{y}) = xy (\frac{21}{xy})
4y+9x=214y + 9x = 21 (Equation 4)
Now we have a system of two linear equations:
x+2y=9x + 2y = 9 (Equation 3)
9x+4y=219x + 4y = 21 (Equation 4)
Solve for xx in Equation 3:
x=92yx = 9 - 2y (Equation 5)
Substitute Equation 5 into Equation 4:
9(92y)+4y=219(9 - 2y) + 4y = 21
8118y+4y=2181 - 18y + 4y = 21
8114y=2181 - 14y = 21
14y=812114y = 81 - 21
14y=6014y = 60
y=6014=307y = \frac{60}{14} = \frac{30}{7}
However, if we substitute the given answer choices into the original equations, we can quickly find the solution.
Let's test option (d) x=1,y=3x = 1, y = 3:
Equation 1: 21+33(3)=21+13=6+13=73\frac{2}{1} + \frac{3}{3(3)} = \frac{2}{1} + \frac{1}{3} = \frac{6+1}{3} = \frac{7}{3}
9xy=91(3)=93=3\frac{9}{xy} = \frac{9}{1(3)} = \frac{9}{3} = 3. So 733\frac{7}{3} \ne 3.
Let's test option (c) x=2,y=3x=2, y=3:
Equation 1: 22+33(3)=1+13=43\frac{2}{2} + \frac{3}{3(3)} = 1 + \frac{1}{3} = \frac{4}{3}
9xy=92(3)=96=32\frac{9}{xy} = \frac{9}{2(3)} = \frac{9}{6} = \frac{3}{2}. So 4332\frac{4}{3} \ne \frac{3}{2}.
Let's try to eliminate x from the two equations:
Multiply the first equation x+2y=9x + 2y = 9 by 9:
9x+18y=819x + 18y = 81
Subtract the second equation 9x+4y=219x + 4y = 21 from this:
(9x+18y)(9x+4y)=8121(9x + 18y) - (9x + 4y) = 81 - 21
14y=6014y = 60
y=6014=307y = \frac{60}{14} = \frac{30}{7}
x=92y=92(307)=9607=63607=37x = 9 - 2y = 9 - 2(\frac{30}{7}) = 9 - \frac{60}{7} = \frac{63-60}{7} = \frac{3}{7}
Now re-examine the original equations. There was a mistake.
Equation 1 should be 2x+1y=9xy\frac{2}{x} + \frac{1}{y} = \frac{9}{xy} which gives 2y+x=92y + x = 9.
Equation 2 is 4x+9y=21xy\frac{4}{x} + \frac{9}{y} = \frac{21}{xy} which gives 4y+9x=214y + 9x = 21.
Multiply Equation 1 by 9 to get 9x+18y=819x+18y = 81.
Subtract Equation 2 from the result: 9x+18y(9x+4y)=81219x+18y - (9x+4y) = 81 - 21, which implies 14y=6014y = 60, or y=307y = \frac{30}{7}.
Multiply Equation 1 by 2 to get 2x+4y=182x+4y = 18.
Subtract Equation 2 from this to get 2x+4y(4y+9x)=18212x+4y - (4y+9x) = 18-21, so 7x=3-7x = -3 which means x=37x = \frac{3}{7}. There's likely an error in the problem statement or OCR.
Let us re-evaluate the problem statement. It is 2x+33y=9xy\frac{2}{x} + \frac{3}{3y} = \frac{9}{xy} and 4x+9y=21xy\frac{4}{x} + \frac{9}{y} = \frac{21}{xy}. This gives us
2y+x=92y + x = 9
4y+9x=214y + 9x = 21
So we have x=92yx = 9-2y. Substitute into the second equation.
4y+9(92y)=214y + 9(9-2y) = 21
4y+8118y=214y + 81 - 18y = 21
14y=60-14y = -60
y=307y = \frac{30}{7}
x=92(307)=63607=37x = 9-2(\frac{30}{7}) = \frac{63 - 60}{7} = \frac{3}{7}
However, if we test x=3 and y=1 (none of the options), the equations are inconsistent.
Try option (d), x=1,y=3x=1, y=3. Then 21+39=2+13=73\frac{2}{1} + \frac{3}{9} = 2+\frac{1}{3} = \frac{7}{3}, and 93=3\frac{9}{3} = 3.
So 73=3\frac{7}{3} = 3 which is wrong.
The problem likely has a typo.

3. Final Answer

None of the answer choices satisfy the given equations. I suspect the equations are inconsistent, or there is a typo in the original problem. If we solve the equations as written, we get x=3/7x=3/7 and y=30/7y=30/7. Therefore, there is no solution here.
If we have to guess and suppose there is a typo and 33y\frac{3}{3y} should have been 3y\frac{3}{y}, then the first equation would have become x+5y=9x+5y=9, and we cannot solve this easily with the provided answers. Assuming there is a typo somewhere, I cannot determine which solution is correct. However, I think (d) is the closest solution.
Final Answer: (d) 1 and 3