Respuesta :
Answer:
So the values of x for which the function is positive are x ≥ -3 and x ≤ -9.
Step-by-step explanation:
We are given a function and we have to find the intervals in which the function has positive value.
y = [tex]x^{2} +12x+27[/tex]
y =(x + 3)(x + 9)
For the function to be positive , y ≥ 0
(x + 3)(x + 9) ≥ 0
Here there are two cases , either both should be positive or both should be negative.
If both are positive,
(x + 3)≥0 and (x + 9)≥0
So, x ≥ -3
If both are negative,
(x + 3)≤0 and (x + 9)≤0
So, x ≤ -9
So the values of x for which the function is positive are x ≥ -3 and x ≤ -9.
The intervals on which the function y = x² + 12x + 27 is positive are
x > -3 and x > -9
For the function given to be positive, it has to be greater than zero.
Since the expression is greater then zero, hence;
x² + 12x + 27 > 0
Factorize the resulting expression
x² + 3x + 9x + 27 > 0
x(x+3) + 9(x+3) > 0
(x+3) (x+9) > 0
x+3 > 0 and x + 9 > 0
x > -3 and x > -9
Hence the intervals on which the function y = x² + 12x + 27 is positive are
x > -3 and x > -9
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