Answer: A) -9
Step-by-step explanation:
If x = -2
Then
= 
So, it is -9
How the quadratic formula works:
For any quadratic equation ax² + bx + c = 0, the solution is

.
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.

There are two values for x: (1+√197)/14 and (1-√197)/14.
The approximate values for these are 1.073976 and -0.931119.
Answer:
<6 = 117 degrees, <7 = 63 degrees
Step-by-step explanation:
- <3 and <6 are consecutive interior angles, meaning they are supplementary.
- <3 and <7 are same-side exterior angles meaning they are congruent.
Answer:
C
Step-by-step explanation:
sorry if I'm wrong-
Answer:
13 is the number.
Step-by-step explanation:
Given:
Twice the difference of a number and 9 equals 8.
Let the unknown number be 'x'.
Therefore, as per question:
The difference of 'x' and 9 = 
Twice the difference means 2 times the difference. So, we multiply 2 to the difference. Therefore,

Now, the above expression is equal to 8. So, we equate the above expression to 8. This gives,

Solving for 'x', we get:
Using distributive property of addition and distributing 2 inside the bracket. This gives,

Therefore, the unknown number is 13.
Now, we can verify our answer.

Therefore, the answer is correct.