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Helpppppppppppppppppp

Helpppppppppppppppppp-example-1

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3 votes
x²-4x-9=29
You need to complete the square by following the next few steps.
First, you need to place the x²-4x into squared brackets, by dividing the coefficient of x by 2x and dividing x² by x:
(x-2)²
Find out what this equals to:
x²-4x+4
We can start off here, as we have obtained the x²-4x. However, we need to get from +4 to -9. To do this, we must minus 13. Therefore, our equation now looks like this:
(x-2)²-13=29
Now, just solve as you normally would, to isolate x:
(x-2)²-13=29
Add 13 on both sides
(x-2)²=42
Square root both sides
x-2=±√42
Add 2 on both sides
x=2±√42
So, your answer is the first option
User Anant Kolvankar
by
8.2k points
4 votes
in this case it is to find the roots of the polynomial.
We have then:
x ^ 2-4x-9 = 29
Rewriting:
x ^ 2-4x-38 = 0
Applying resolver we have
x = (- b +/- root (b ^ 2 - 4ac)) / (2a)
Substituting values:
x = (- (- 4) +/- root ((- 4) ^ 2 - 4 (1) (- 38))) / (2 (1))
x = (4 +/- root (16 + 152))) / (2)
x = (2 +/- root (42))
Answer:
x = (2 +/- root (42))
(option1)
User Yaser Darzi
by
7.4k points

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