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Andre45 [30]
2 years ago
11

Solve by completing the square​

Mathematics
1 answer:
erastovalidia [21]2 years ago
5 0

Answer:

Your answers would be:

x = 10 and x = -8

Step-by-step explanation:

Solve for the zeros:

x² - 2x - 78 = 2

Subtract both sides by 2.

x² - 2x - 80 = 0

Use the quadratic formula: x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}

a = 1

b = -2

c = -80

Plug in and solve:

x=\frac{-(-2)\pm\sqrt{(-2)^2-4(1)(-80)}}{2(1)}\\\\x=\frac{2\pm\sqrt{(-2)^2-4(1)(-80)}}{2(1)}\\\\x=\frac{2\pm\sqrt{4-4(-80)}}{2(1)}\\\\x=\frac{2\pm\sqrt{4+320}}{2(1)}\\\\x=\frac{2\pm\sqrt{324}}{2(1)}\\\\x=\frac{2\pm18}{2}\\

Solve for +:

x=\frac{2+18}{2}\\\\x=\frac{20}{2}\\\\x=10

Solve for -:

x=\frac{2-18}{2}\\\\x=\frac{-16}{2}\\\\x=-8

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