Answered

Find the real solution of the following radical equation.

[tex]\[
\begin{array}{c}
a = \sqrt{5a + 6} \\
a = \, [?]
\end{array}
\][/tex]



Answer :

To solve the radical equation [tex]\( a = \sqrt{5a + 6} \)[/tex], let's proceed step-by-step.

1. Isolate the square root term:
[tex]\[ a = \sqrt{5a + 6} \][/tex]

2. Square both sides of the equation to eliminate the square root:
[tex]\[ a^2 = ( \sqrt{5a + 6} )^2 \][/tex]
[tex]\[ a^2 = 5a + 6 \][/tex]

3. Rearrange the equation to standard quadratic form:
[tex]\[ a^2 - 5a - 6 = 0 \][/tex]

4. Solve the quadratic equation using the quadratic formula, [tex]\( a = \frac{{-b \pm \sqrt{{b^2-4ac}}}}{2a} \)[/tex], where [tex]\( a = 1 \)[/tex], [tex]\( b = -5 \)[/tex], and [tex]\( c = -6 \)[/tex]:

[tex]\[ a = \frac{{-(-5) \pm \sqrt{{(-5)^2 - 4(1)(-6)}}}}{2(1)} \][/tex]
[tex]\[ a = \frac{{5 \pm \sqrt{{25 + 24}}}}{2} \][/tex]
[tex]\[ a = \frac{{5 \pm \sqrt{49}}}{2} \][/tex]
[tex]\[ a = \frac{{5 \pm 7}}{2} \][/tex]

5. Find the two potential solutions:

For the positive case:
[tex]\[ a = \frac{5 + 7}{2} = \frac{12}{2} = 6 \][/tex]

For the negative case:
[tex]\[ a = \frac{5 - 7}{2} = \frac{-2}{2} = -1 \][/tex]

6. Check each solution in the original equation to verify it's valid:

For [tex]\( a = 6 \)[/tex]:
[tex]\[ 6 = \sqrt{5(6) + 6} \][/tex]
[tex]\[ 6 = \sqrt{30 + 6} \][/tex]
[tex]\[ 6 = \sqrt{36} \][/tex]
[tex]\[ 6 = 6 \][/tex]

This solution is valid.

For [tex]\( a = -1 \)[/tex]:
[tex]\[ -1 = \sqrt{5(-1) + 6} \][/tex]
[tex]\[ -1 = \sqrt{-5 + 6} \][/tex]
[tex]\[ -1 = \sqrt{1} \][/tex]
[tex]\[ -1 = 1 \][/tex]

This solution is invalid due to the square root producing a positive result, while the left side is negative.

Therefore, the real solution to the equation [tex]\( a = \sqrt{5a + 6} \)[/tex] is:
[tex]\[ a = 6 \][/tex]