Complete the square to solve the following quadratic equation: x2−22x+1=15 .(1 point)

Responses

x=11+14−−√, 11−14−−√
x equals 11 plus Start Root 14 End Root comma 11 minus Start Root 14 End Root

x=−11+14−−√, −11−14−−√
x equals negative 11 plus Start Root 14 End Root comma negative 11 minus Start Root 14 End Root

x=−11+315−−√, −11−315−−√
x equals negative 11 plus 3 Start Root 15 End Root comma negative 11 minus 3 Start Root 15 End Root

x=11+315−−√, 11−315−−√

1 answer

To complete the square for the quadratic equation \( x^2 - 22x + 1 = 15 \), we first rearrange the equation to set it equal to zero:

\[ x^2 - 22x + 1 - 15 = 0 \] \[ x^2 - 22x - 14 = 0 \]

Next, we can complete the square. We take the coefficient of \( x \) (which is \(-22\)), divide it by 2 (getting \(-11\)), and square it (getting \(121\)). We then add and subtract \(121\) in the equation:

\[ x^2 - 22x + 121 - 121 - 14 = 0 \] \[ (x - 11)^2 - 135 = 0 \]

Next, we move \(135\) to the other side:

\[ (x - 11)^2 = 135 \]

Now, we take the square root of both sides:

\[ x - 11 = \pm \sqrt{135} \]

Then we solve for \(x\):

\[ x = 11 \pm \sqrt{135} \]

Thus, the solutions are:

\[ x = 11 + \sqrt{135} \quad \text{and} \quad x = 11 - \sqrt{135} \]

The value of \(\sqrt{135}\) can be simplified to \(3\sqrt{15}\), so the final solutions can be expressed as:

\[ x = 11 + 3\sqrt{15}, \quad x = 11 - 3\sqrt{15} \]

Therefore, the correct responses are:

\[ x = 11 + 3\sqrt{15}, \quad 11 - 3\sqrt{15} \]