How to solve this:

-3 √(6x+5) = -9

Do we use conjugate of -3 √(6x+5)? If so, what is the conjugate of -3 √(6x+5)?

example: The conjugate of (x + √y) is (x - √y).

I don't think the conjugate of -3 √(6x+5) is -3 √(6x-5) since the above example has 2 terms, that is x and √y while -3 √(6x+5) is only 1 term.

Thanks.

2. Originally Posted by shenton
How to solve this:

-3 √(6x+5) = -9

You start by squaring to get:

$
\left[ -3 \sqrt{6x+5}\right]^2 = (-9)^2
$

which simplifies to:

$
9 (6x+5) = 9^2
$

further simplification gives:

$
6x = 4
$

which si,plifies further to $x=2/3$.

Now as we squared the original equation we need to check that
any solution we subsequently find satisfies the original equation
as squaring can introduce spurious solutions. But in this case there
is no problem and $x=2/3$ is the solution.

RonL

3. Thanks for the help!