Question

When completing the square on the equation c2 + 110 = 12, the resulting solution is: It

Answer 1

Answer:

$c=1$ and $c=-12$

Step-by-step explanation:

The correct equation is:

$c^2+11c=12$

To solve by completing the square method.

Solution:

We have:

$c^2+11c=12$

In order to solve by completing the square method we will carry out the following operations to the given equation to get a perfect square binomial.

We can write as:

$c^2+2.\frac{11}{2}c=12$  

$c^2+2.\frac{11}{2}c+(\frac{11}{2})^2-(\frac{11}{2})^2=12$

$(c+\frac{11}{2})^2-(\frac{11}{2})^2=12$  [As  $c^2+2.\frac{11}{2}c+(\frac{11}{2})^2=(c+\frac{11}{2})^2$]

Adding both sides by $(\frac{11}{2})^2$

$(c+\frac{11}{2})^2-(\frac{11}{2})^2+(\frac{11}{2})^2=12+(\frac{11}{2})^2$

$(c+\frac{11}{2})^2=12+\frac{121}{4}$  

Taking LCD to add fraction.

$(c+\frac{11}{2})^2=\frac{48}{4}+\frac{121}{4}$

$(c+\frac{11}{2})^2=\frac{169}{4}$

Taking square root both sides.

$\sqrt{(c+\frac{11}{2})^2}=\sqrt{\frac{169}{4}}$

$c+\frac{11}{2}=\pm\frac{13}{2}$

Subtracting both sides by $\frac{11}{2}$ :

$c+\frac{11}{2}-\frac{11}{2}=\pm\frac{13}{2}-\frac{11}{2}$

$c=\pm\frac{13}{2}-\frac{11}{2}$

So, we have:

$c=\frac{13}{2}-\frac{11}{2}$ and $c=-\frac{13}{2}-\frac{11}{2}$

$c=\frac{2}{2}$ and $c=\frac{-24}{2}$

$c=1$ and $c=-12$  (Answer)