Consider this quadratic equation X^2+2x+7=21

Mathematics

1 answer:

nadya68 [22]3 years ago

8 0

Answer:

x = sqrt(15) - 1 or x = -1 - sqrt(15)

Step-by-step explanation:

Solve for x:

x^2 + 2 x + 7 = 21

Subtract 7 from both sides:

x^2 + 2 x = 14

Add 1 to both sides:

x^2 + 2 x + 1 = 15

Write the left hand side as a square:

(x + 1)^2 = 15

Take the square root of both sides:

x + 1 = sqrt(15) or x + 1 = -sqrt(15)

Subtract 1 from both sides:

x = sqrt(15) - 1 or x + 1 = -sqrt(15)

Subtract 1 from both sides:

Answer: x = sqrt(15) - 1 or x = -1 - sqrt(15)

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