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

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.