157k views
5 votes
Using the quadratic formula to solve 7x2 – x = 7, what are the values of x?

User Startec
by
7.8k points

2 Answers

7 votes

Answer:

B

Explanation:

Just took the test B==D

User Ulf Holm Nielsen
by
8.5k points
3 votes
Your answers are x = 1.074 and x = -0.931
You first make the equation equal 0 by subtracting 7, and you get 7x² - x - 7 = 0.
In the quadratic formula, which is
(-b +- √b² - 4ac)/2a, a is the x², which is 7, b is the x, which is -1, and c is the value, which is -7. This means we can substitute those into our formula and get
(1 +- √-1² - 4 × 7 × -7)/2 × 7
The way I like to solve this is by figuring out the part inside the square root first, which is -1² - 4 × 7 × -7 = 197. Now we use that when substituting with plus and with minus, so:
(1 + √197)/14 = 1.074
(1 - √197)/14 = -0.931

I hope this helps! I'm not sure if it makes total sense so let me know if you want me to go over it a bit more :)
User Robin Varghese
by
7.9k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories