College

The product of two consecutive odd integers is less than 76, where [tex] n [/tex] is the first odd integer.

A. [tex] n(n+1) < 76 [/tex]
B. [tex] n(n+1) > 76 [/tex]
C. [tex] n(n+2) < 76 [/tex]
D. [tex] n(n+2) \geq 76 [/tex]

Answer :

Sure! Let's solve the problem step-by-step.

The problem involves finding two consecutive odd integers whose product is less than 76. The first odd integer is denoted by [tex]\( n \)[/tex].

Odd integers increase by 2, so the two consecutive odd integers can be represented as [tex]\( n \)[/tex] and [tex]\( n + 2 \)[/tex].

The inequality we are dealing with is:

[tex]\[ n(n + 2) < 76 \][/tex]

To find the range of values for [tex]\( n \)[/tex], we will solve this inequality.

1. Set up the inequality:

[tex]\[ n(n + 2) < 76 \][/tex]

Expanding this, we have:

[tex]\[ n^2 + 2n < 76 \][/tex]

2. Rearrange the inequality:

Subtract 76 from both sides to form a quadratic inequality:

[tex]\[ n^2 + 2n - 76 < 0 \][/tex]

3. Solve the quadratic inequality:

To solve the quadratic inequality, we first determine the roots of the quadratic equation:

[tex]\[ n^2 + 2n - 76 = 0 \][/tex]

The roots are found using the quadratic formula:

[tex]\[ n = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]

Here, [tex]\( a = 1 \)[/tex], [tex]\( b = 2 \)[/tex], and [tex]\( c = -76 \)[/tex].

[tex]\[ n = \frac{-2 \pm \sqrt{2^2 - 4 \cdot 1 \cdot (-76)}}{2 \cdot 1} \][/tex]

[tex]\[ n = \frac{-2 \pm \sqrt{4 + 304}}{2} \][/tex]

[tex]\[ n = \frac{-2 \pm \sqrt{308}}{2} \][/tex]

[tex]\[ n = \frac{-2 \pm \sqrt{4 \cdot 77}}{2} \][/tex]

[tex]\[ n = \frac{-2 \pm 2\sqrt{77}}{2} \][/tex]

[tex]\[ n = -1 \pm \sqrt{77} \][/tex]

Therefore, the roots are [tex]\( n = -1 + \sqrt{77} \)[/tex] and [tex]\( n = -1 - \sqrt{77} \)[/tex].

4. Determine the intervals:

Since we're looking for the values of [tex]\( n \)[/tex] that make the quadratic expression less than 0, we examine the number line and determine that [tex]\( n \)[/tex] is between the two roots.

Thus, the solution for [tex]\( n \)[/tex] is:

[tex]\(-1 - \sqrt{77} < n < -1 + \sqrt{77}\)[/tex]

This interval represents the values for [tex]\( n \)[/tex] where the product of the two consecutive odd integers is less than 76.