Select the correct answer.

Which equation is equivalent to the given equation?

[tex]\[ x^2 + 16x = 22 \][/tex]

A. [tex]\((x + 16)^2 = 278\)[/tex]

B. [tex]\((x + 8)^2 = 86\)[/tex]

C. [tex]\((x + 4)^2 = 22\)[/tex]

D. [tex]\((x + 8)^2 = 38\)[/tex]



Answer :

Certainly! Let's solve the equation step-by-step.

The given equation is:
[tex]\[ x^2 + 16x = 22 \][/tex]

To convert this equation into a perfect square form, we need to complete the square. Here are the steps:

1. Identify the coefficient of the linear term (the term with [tex]\( x \)[/tex]). In this case, the coefficient is [tex]\( 16 \)[/tex].

2. Halve this coefficient, and then square the result. Halving [tex]\( 16 \)[/tex] gives [tex]\( 8 \)[/tex], and squaring [tex]\( 8 \)[/tex] gives [tex]\( 64 \)[/tex]:

[tex]\[ \left(\frac{16}{2}\right)^2 = 8^2 = 64 \][/tex]

3. Add and subtract this square (i.e., [tex]\( 64 \)[/tex]) inside the equation to maintain the equality:

[tex]\[ x^2 + 16x + 64 - 64 = 22 \][/tex]
[tex]\[ x^2 + 16x + 64 = 22 + 64 \][/tex]

4. Observe that the left-hand side is now a perfect square trinomial.

5. Rewrite the trinomial as a square of a binomial:

[tex]\[ (x + 8)^2 = 86 \][/tex]

So, the equation [tex]\( x^2 + 16x = 22 \)[/tex] is equivalent to:

[tex]\[ (x + 8)^2 = 86 \][/tex]

Hence, the correct answer is:
[tex]\[ \boxed{(x+8)^2=86} \][/tex]

Thus, option B is the correct one.