1. Solve the system \(y = 3x - 5\) and \(5x + 4y = -3\).
Substitute \(y\) from the first equation into the second:
$$5x + 4(3x - 5) = -3$$
$$5x + 12x - 20 = -3$$
$$17x - 20 = -3$$
$$17x = 17$$
$$x = 1$$
Find \(y\):
$$y = 3(1) - 5 = 3 - 5 = -2$$
Solution: \((x,y) = (1, -2)\).
2. Solve the system \(x = 2y - 1\) and \(7x + 2y = 25\).
Substitute \(x\) into the second equation:
$$7(2y - 1) + 2y = 25$$
$$14y - 7 + 2y = 25$$
$$16y - 7 = 25$$
$$16y = 32$$
$$y = 2$$
Find \(x\):
$$x = 2(2) - 1 = 4 - 1 = 3$$
Solution: \((x,y) = (3, 2)\).
3. Solve the system \(2x + y = 5\) and \(x - 2y = 5\).
Multiply the second equation by 2 to align \(y\) terms:
$$2(x - 2y) = 2(5)$$
$$2x - 4y = 10$$
Subtract the first equation from this:
$$(2x - 4y) - (2x + y) = 10 - 5$$
$$2x - 4y - 2x - y = 5$$
$$-5y = 5$$
$$y = -1$$
Find \(x\):
$$2x + (-1) = 5$$
$$2x = 6$$
$$x = 3$$
Solution: \((x,y) = (3, -1)\).
4. Solve the system \(2x - 3y = 11\) and \(x - y = 4\).
Multiply the second equation by 3:
$$3(x - y) = 3(4)$$
$$3x - 3y = 12$$
Subtract the first equation from this:
$$(3x - 3y) - (2x - 3y) = 12 - 11$$
$$3x - 3y - 2x + 3y = 1$$
$$x = 1$$
Find \(y\):
$$1 - y = 4$$
$$-y = 3$$
$$y = -3$$
Solution: \((x,y) = (1, -3)\).
Each system represents two lines; their solution is the intersection point.
Desmos functions for each system:
1. \(y = 3x - 5\) and \(y = \frac{-5x - 3}{4}\)
2. \(y = \frac{x + 1}{2}\) and \(7x + 2y = 25\)
3. \(y = 5 - 2x\) and \(y = \frac{x - 5}{2}\)
4. \(y = x - 4\) and \(y = \frac{2x - 11}{3}\)
Linear Systems 2Aca15
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