Completing the square

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

What do you do to the b value to correctly complete the square?

• square it
• divide it by 2 and square the result
• divide it by 2 and take the square root of the result
• divide it by 2 only

When factoring
x² - 4x + 4 = 20,
what goes in the blank?
(x - __ )² = 20

• 4
• 2
• 8
• 20

What value of c would make this a perfect sqaure trinomial?
x² +8x + c

• 4
• 16
• 64
• -16

Complete the Square
x² + 6x = 5

• (x + 3)² = 5
• (x + 6)² = 9
• (x + 3)² = 14
• (x + 6)² = 14

Solve by completing the square:
k² − 12k + 23 = 0

• {6 + √13, 6 - √13}
• {-6 + √13, -6 - √13}
• {6 + √59, 6 - √59}
• {-6 + √59, -6 - √59}

Solve by completing the square.
y² + 10y = -9

• 1 and -12
• -1 and -9
• 1 and -9
• 1 and -1

Find the value of "c" that completes the square.

 $x^2+28x+c$  

• 28

• 14

• 196

• 56

When factoring  $x^2-10x+25\ =\ 49$  
what goes into the blank   $\left(x-\ldots\right)^2=49$  

• 5

• 10

• 7

• 25

Solve by completing the square. Round.
x² -4x = 5

• 11 and -7
• 1 and 3
• 1.73 and -1.73
• 5 and -1