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Solve Simaltoinecusly \( 3 x-4 y=5 \) and \( 2 x^{2}-5 x y+3 y^{2}=4 \)

Ask by Washington Stanley. in South Africa
Feb 18,2025

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Answer

The solutions are \( (x, y) = (-1, -2) \) and \( (x, y) = (11, 7) \).

Solution

Solve the system of equations \( 3x-4y=5;2x^{2}-5xy+3y^{2}=4 \). Solve the system of equations by following steps: - step0: Solve using the substitution method: \(\left\{ \begin{array}{l}3x-4y=5\\2x^{2}-5xy+3y^{2}=4\end{array}\right.\) - step1: Solve the equation: \(\left\{ \begin{array}{l}x=\frac{5+4y}{3}\\2x^{2}-5xy+3y^{2}=4\end{array}\right.\) - step2: Substitute the value of \(x:\) \(2\left(\frac{5+4y}{3}\right)^{2}-5\times \frac{5+4y}{3}\times y+3y^{2}=4\) - step3: Simplify: \(\frac{50}{9}+\frac{80}{9}y+\frac{59}{9}y^{2}-\frac{5\left(5+4y\right)y}{3}=4\) - step4: Multiply both sides of the equation by LCD: \(\left(\frac{50}{9}+\frac{80}{9}y+\frac{59}{9}y^{2}-\frac{5\left(5+4y\right)y}{3}\right)\times 9=4\times 9\) - step5: Simplify the equation: \(50+5y-y^{2}=36\) - step6: Move the expression to the left side: \(50+5y-y^{2}-36=0\) - step7: Subtract the numbers: \(14+5y-y^{2}=0\) - step8: Factor the expression: \(\left(7-y\right)\left(2+y\right)=0\) - step9: Separate into possible cases: \(\begin{align}&7-y=0\\&2+y=0\end{align}\) - step10: Solve the equation: \(\begin{align}&y=7\\&y=-2\end{align}\) - step11: Calculate: \(y=7\cup y=-2\) - step12: Rearrange the terms: \(\left\{ \begin{array}{l}x=\frac{5+4y}{3}\\y=7\end{array}\right.\cup \left\{ \begin{array}{l}x=\frac{5+4y}{3}\\y=-2\end{array}\right.\) - step13: Calculate: \(\left\{ \begin{array}{l}x=11\\y=7\end{array}\right.\cup \left\{ \begin{array}{l}x=-1\\y=-2\end{array}\right.\) - step14: Calculate: \(\left\{ \begin{array}{l}x=-1\\y=-2\end{array}\right.\cup \left\{ \begin{array}{l}x=11\\y=7\end{array}\right.\) - step15: Check the solution: \(\left\{ \begin{array}{l}x=-1\\y=-2\end{array}\right.\cup \left\{ \begin{array}{l}x=11\\y=7\end{array}\right.\) - step16: Rewrite: \(\left(x,y\right) = \left(-1,-2\right)\cup \left(x,y\right) = \left(11,7\right)\) The solutions to the system of equations \(3x-4y=5\) and \(2x^{2}-5xy+3y^{2}=4\) are \((x,y) = (-1,-2)\) and \((x,y) = (11,7)\).

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To solve the equations simultaneously, we start with the linear equation \(3x - 4y = 5\). We can express \(y\) in terms of \(x\): \[ 4y = 3x - 5 \implies y = \frac{3x - 5}{4} \] Now we substitute \(y\) into the quadratic equation \(2x^2 - 5xy + 3y^2 = 4\): \[ 2x^2 - 5x\left(\frac{3x - 5}{4}\right) + 3\left(\frac{3x - 5}{4}\right)^2 = 4 \] Multiplying through by 4 to eliminate the fraction gives: \[ 8x^2 - 5x(3x - 5) + 3(3x - 5)^2 = 16 \] Expanding the terms: \[ 8x^2 - 15x^2 + 25x + 3(9x^2 - 30x + 25) = 16 \] This simplifies to: \[ 8x^2 - 15x^2 + 25x + 27x^2 - 90x + 75 = 16 \] Combining like terms results in: \[ (8 - 15 + 27)x^2 + (25 - 90)x + 75 - 16 = 0 \] \[ 20x^2 - 65x + 59 = 0 \] Now we can use the quadratic formula to find \(x\): \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{65 \pm \sqrt{(-65)^2 - 4 \cdot 20 \cdot 59}}{2 \cdot 20} \] Calculating the discriminant: \[ 65^2 - 4 \cdot 20 \cdot 59 = 4225 - 4720 = -495 \] Since the discriminant is negative, there are no real solutions for \(x\). This implies that the system of equations does not have any points of intersection in the real number plane, meaning the lines described by the equations do not meet.

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