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What number would you add to both sides of [tex]$x^2 + 7x = 4$[/tex] to complete the square?

A. [tex]$2^2$[/tex]
B. [tex][tex]$7^2$[/tex][/tex]
C. [tex]$\frac{7^2}{2}$[/tex]
D. [tex]$\left(\frac{7}{2}\right)^2$[/tex]


Sagot :

To complete the square for the quadratic equation [tex]\( x^2 + 7x = 4 \)[/tex], follow these step-by-step instructions:

1. Identify the coefficient of the linear term (the term with [tex]\( x \)[/tex]):
- The coefficient of [tex]\( x \)[/tex] in [tex]\( x^2 + 7x \)[/tex] is 7.

2. Divide the linear coefficient by 2:
- [tex]\(\frac{7}{2}\)[/tex].

3. Square the result of the division:
- [tex]\(\left(\frac{7}{2}\right)^2 = \left(\frac{7}{2}\right) \times \left(\frac{7}{2}\right) = \frac{49}{4}\)[/tex].

To match the numerical result provided earlier:
- [tex]\(\left(\frac{7}{2}\right)^2 = 12.25\)[/tex]

So, the number you would add to both sides of [tex]\( x^2 + 7x = 4 \)[/tex] to complete the square is:
- [tex]\(\left(\frac{7}{2}\right)^2\)[/tex].

Hence, the correct option is:
- [tex]\(\left(\frac{7}{2}\right)^2\)[/tex].