Use completing the square to solve for x in the equation (x minus 12) (x + 4) = 9. x = –1 or 15 x = 1 or 7 x = 4 plus-or-minus S
2 answers:
Answer:
x = 4 ±
Step-by-step explanation:
Given
(x - 12)(x + 4) = 9 ← expand the left side using FOIL
x² - 8x - 48 = 9 ( ad 48 to both sides )
x² - 8x = 57
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(- 4)x + 16 = 57 + 16
(x - 4)² = 73 ( take the square root of both sides )
x - 4 = ± ( add 4 to both sides )
x = 4 ±
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Answer:
[Vertex form]
Step-by-step explanation:
Given function:
We need to find the vertex form which is.,
where represents the co-ordinates of vertex.
We apply completing square method to do so.
We have
First of all we make sure that the leading co-efficient is =1.
In order to make the leading co-efficient is =1, we multiply each term with -3.
Isolating and
terms on one side.
Subtracting both sides by 15.
In order to make the right side a perfect square trinomial, we will take half of the co-efficient of term, square it and add it both sides side.
square of half of the co-efficient of term =
Adding 36 to both sides.
Since is a perfect square of
, so, we can write as:
Subtracting 21 to both sides:
Dividing both sides by -3.
[Vertex form]