Solving Equations and Complex Numbers

What is the first step to solving THIS equation by completing the square?
a² + 10a + 21 = 0

• Set the equation equal to zero

• Divide 10 by 2 and add the result to both sides

• Add a² and 10a together

• Subtract the 21

Solve the following quadratics equation by completing the square... x² + 4x + 1 = 0

• x = -2 ± √3

• x = -3 ± √2

• x = 2 ± √3

• x = 2 ± √2

Solve the equation by completing the square and then finding the roots. 
x²+ 6x - 4 = 36

• x = -7, 7

• x = 4, -10

• x = -4 +- √7

• x = 10, -4

• {49,-49}

• {8,-8}

• {7,-7}

• No Solution

i(2+5i)

• -5+2i

• 5-2i

• 7i

• 2i+5i

Which of the following is equivalent to (5-3i)+(-6+2i)?

• -1-5i

• -1-i

• 11-i

• -30-6i

(2+3i)(4-2i)

• 14+8i

• 48+16i

• 12-8i

• 2-8i

Simplify √-4

• 2i

• -2i

• 2

• 4i

Simplify √-81

• -√81

• -9i

• 9i

• 81i

(9-6i)+(-2+13i)

• 7+7i

• -28-78i

• 11-19i

• 7-7i