Please, use " ^ " to denote exponentiation: x^2 + 4x - 21 = 0
Factor: (x+7)(x-3)=0
Solve for the 2 roots: x= -7 and x= 3: {3, -7} Note how this is in set notation.
Answer: the correct option is
(C) 3, -7.
Step-by-step explanation: We are given to solve the following equation for x :
[tex]x^2+4x-21=0~~~~~~~~~~~~~~~~~~~~~~~```(i)[/tex]
We will be solving the given quadratic equation by factorization.
The solution of equation (i) is as follows :
[tex]x^2+4x-21=0\\\\\Rightarrow x^2+7x-3x-21=0\\\\\Rightarrow x(x+7)-3(x+7)=0\\\\\Rightarrow (x-3)(x+7)=0\\\\\Rightarrow x-3=0,~~~x+7=0\\\\\Rightarrow x=3,~-7.[/tex]
Thus, the required values of x are
x = 3, -7.
Option (C) is CORRECT.
