We notice that the denominator of the first ratio is the
result of expanding the square (x+3)^2.
We've applied the
formula:
(a+b)^2 = a^2 + 2ab +
b^2
So, x^2+6x+9 =
x^2+2*3*x+(3)^2
We'll re-write the
equation:
1/(x+3)^2 + 1/(x+3) =
4/9
The least common denominator is
9(x+3)^2.
We'll multiply the first ratio by 9, the second
ratio by 9(x+3) and the third ratio by (x+3)^2.
We'll
re-write the equation, without denominators.
9 + 9(x+3) =
4(x+3)^2
We'll remove the brackets from the left side and
we'll expand the square from the right side:
9 + 9x + 27 =
4x^2 + 24x + 36
We'll subtract 4x^2 + 24x + 36 both
sides:
9 + 9x + 27 - 4x^2 - 24x - 36 =
0
We'll combine like terms:
-
4x^2 - 15x = 0
We'll factorize by
-x:
-x(4x + 15) = 0
We'll set
each factor as zero:
-x = 0
x
= 0
4x + 15 = 0
We'll subtract
15:
4x = -15
We'll divide by
4:
x =
-15/4.
The solutions of the equation are:
{-15/4 ; 0}.
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