Answer:
<em>Solutions: </em>
a) x = 0, y = 4 ⇒ (0, 4)
b) x = -1, y = 0 ⇒ (-1, 0)
Step-by-step explanation:
Given system of equations:
a) y = 2x² + 6x + 4
b) y = -4x² + 4
1. Substitute the value of y in the <em>second</em> equation into the <em>first </em>equation:
⇒ -4x² + 4 = 2x² + 6x + 4
2. Solve for x:
⇒ -4x² + 4 = 2x² + 6x + 4 [subtract 4 from both sides]
⇒ -4x² + 4 - 4 = 2x² + 6x + 4 - 4
⇒ -4x² = 2x² + 6x [subtract 2x² from both sides]
⇒ -4x² - 2x² = 2x² - 2x² + 6x
⇒ -6x² = 6x [subtract 6x from both sides]
⇒ -6x² - 6x = 6x - 6x
⇒ -6x² - 6x = 0 [factor out -6x from the equation]
⇒ -6x(x + 1) = 0
Two cases:
a)
⇒ -6x = 0 [divide both sides by -6]
⇒ -6x ÷ -6 = 0 ÷ -6
⇒ x = 0
b)
⇒ x + 1 = 0 [subtract 1 from both sides]
⇒ x + 1 - 1 = 0 - 1
⇒ x = -1
3. Find the value of y by substituting the found x values into one of the given equations:
a) x = 0:
⇒ y = -4x² + 4
⇒ y = -4(0)² + 4
⇒ y = -4(0) + 4
⇒ y = = 0 + 4
⇒ y = 4
coordinate: (0, 4)
b) x = -1:
⇒ y = -4x² + 4
⇒ y = -4(-1)² + 4
⇒ y = -4(1) + 4
⇒ y = -4 + 4
⇒ y = 0
coordinate: (-1, 0)
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