Solve the quadratic equation by completing the square.

x^2 + 12x +21 = 0

first, choose the appropriate form and fill in the blanks with the correct numbers.
then, solve the equation. round your answer to the nearest hundredth.
if there is more than one solution, separate them with commas.

form:
a. (x+_ ) ^2 = _
b. ( = _

solution:
x= _

Step-by-step explanation:

Given is a quadratic equation.

Subtract 21 from both the sides

Here a=1, b =12

Hence find

Hence we get

show us the picture

step-by-step explanation:

show the !

- 2 + 10x³ - 21x² + 19x - 4

step-by-step explanation:

each term in the second factor is multiplied by each term in the first factor

x²(- 2x² + 4x - 1) - 3x(- 2x² + 4x - 1) + 4(- 2x² + 4x - 1) ← distribute

= - 2 + 4x³ - x² + 6x³ - 12x² + 3x -8x² + 16x - 4

collect like terms

= - 2 + 10x³ - 21x² + 19x - 4 ← in standard form