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11. What is the positive solution to this equation?
4x2+ 12 x= 28

User Kriyeta
by
4.0k points

1 Answer

3 votes

Answer:

x = sqrt(37)/2 - 3/2

approximately 1.54

Explanation:

Solve for x over the real numbers:

4 x^2 + 12 x = 28

Divide both sides by 4:

x^2 + 3 x = 7

Add 9/4 to both sides:

x^2 + 3 x + 9/4 = 37/4

Write the left hand side as a square:

(x + 3/2)^2 = 37/4

Take the square root of both sides:

x + 3/2 = sqrt(37)/2 or x + 3/2 = -sqrt(37)/2

Subtract 3/2 from both sides:

x = sqrt(37)/2 - 3/2 or x + 3/2 = -sqrt(37)/2

Subtract 3/2 from both sides:

Answer: |

| x = sqrt(37)/2 - 3/2 or x = -3/2 - sqrt(37)/2