Question 715346: B^2+9b+20=0
Answer by Simnepi(216)   (Show Source):
You can put this solution on YOUR website! to solve quadratic equations the first thing is to look for factor pairs of the constant term, in this case that is +20.
factors of +20 are: (remember either these have to be both positive or both negative numbers because negative multiplied by negative gives a positive answer)
plus/minus 1 and 20:
plus/minus 2 and 10:
Plus/minus 4 and 5.
Now we look to see if any of those factor pairs can be added to make the coefficient of the x term (that's the number in front of the x) which is +9.
Obviously the factor pair we need are plus 4 and 5 because 4 + 5 = 9
Now we get two brackets and put an x in both and one of the factors in each bracket
Like this
(x+4)(x+5)
making this equal zero means that either one of these brackets could equal zero, that is,
either (x+4)=0 or (x+5)=0
If (x+4)=0 then x = -4
OR
If (x+5)=0 then x = -5
These are the two solutions
x = -4 or -5
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