Which option shows the correct substitution of values into the quadratic formula for the equation 7m

2
−m=6?

m=
2(1)
−(−1)±
(1)
2
+4(7)(6)





m=
2(7)
−(−1)±
(−1)
2
−4(7)(−6)





m=
2⋅7
−1±
−1
2
−4⋅7⋅−6





m=
2

1−4(7)(−6)


1 answer

To solve the quadratic equation \(7m^2 - m = 6\), we first need to rewrite it in standard form, which is \(ax^2 + bx + c = 0\).

Rearranging the equation, we get:

\[ 7m^2 - m - 6 = 0 \]

Here, we can identify:

  • \(a = 7\)
  • \(b = -1\)
  • \(c = -6\)

Now, we can substitute these values into the quadratic formula, which is:

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

Substituting \(a\), \(b\), and \(c\) into the formula:

\[ m = \frac{{-(-1) \pm \sqrt{{(-1)^2 - 4(7)(-6)}}}}{{2(7)}} \]

Simplifying this:

\[ m = \frac{{1 \pm \sqrt{{1 + 168}}}}{{14}} \]

\[ m = \frac{{1 \pm \sqrt{{169}}}}{{14}} \]

\[ m = \frac{{1 \pm 13}}{{14}} \]

Now let's check which option correctly reflects this substitution.

  1. First Option: \(m = \frac{{2(1)}}{{-(-1) \pm (1)^2 + 4(7)(6)}}\) - Incorrect, as it doesn't match.

  2. Second Option: \(m = \frac{{2(7)}}{{-(-1) \pm (-1)^2 - 4(7)(-6)}}\) - Incorrect, as here \(c\) is used positively.

  3. Third Option: \(m = \frac{{2 \cdot 7}}{{-1 \pm (-1)^2 - 4 \cdot 7 \cdot -6}}\) - Incorrect substitution of constants.

  4. Fourth Option: \(m = \frac{{2}}{{1 \pm (1 - 4(7)(-6))}}\) - Incorrect as the structure doesn't represent the quadratic formula correctly.

None of the options provided match the appropriate substitution for the quadratic formula for this equation.

Correct substitution should be:

\[ m = \frac{{-(-1) \pm \sqrt{{(-1)^2 - 4(7)(-6)}}}}{{2(7)}} \]

If you have to select an option based on common forms, none appear valid from the answers supplied. Please double-check the proposed choices or review for typographical errors.