Question

Using the quadratic formula to solve 7x2 – x = 7, what are the values of x?

Answer 1

Answer:c

Step-by-step explanation:

Answer 2

How the quadratic formula works:

For any quadratic equation ax² + bx + c = 0, the solution is $x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$.

In the case of our equation 7x² - x = 7, first we need to subtract 7 from each side so that we have 0 on the right.
7x² - x - 7 = 0

Identify the values of a, b, and c.
a = 7, b = -1, and c = -7.

Plug these into our quadratic formula and solve.

$x=\frac{-(-1)\pm\sqrt{(-1)^2-4(7)(-7)}}{2(7)}=\boxed{\frac{1\pm\sqrt{197}}{14}$

There are two values for x: (1+√197)/14 and (1-√197)/14.
The approximate values for these are 1.073976 and -0.931119.