X^2 - 10x + 8 =0
x^2 - 10 + (-10/2)^2 - (-10/2)^2 + 8 = 0
(x - 5)^2 - 25 + 8 = 0
(x - 5)^2 - 17 = 0
To be honest , this is the final step for this equation. It seems like there is no any suitable answer for this question..
To me , I think the best answer will be the third option.
x - 5 =0
x = 5
2x-10 = 0
2x = 10
x = 5
I guess this answer seems like legit.. So I will choose the third option.
Answer:

Step-by-step explanation:
See pic.
Answer:
B. 7x - 5
Explanation
Given the expression 21x^2 + 13x – 20, to get which of the given expression is a factor we will have to factorize the equation first as shown;
21x^2 + 13x – 20
= 21x^2 + 28x - 15x - 20
= 7x(3x+4) -5(3x+4)
= (7x-5)(3x+4)
Hence one of the factors is 7x - 5
The answer for the inverse is X= -1