Answer:
x = 3 and -7
Explanations:
Given the quadratic equation as shown;
[tex]x^2+4x-21=0[/tex]
Factorize the expression
[tex]\begin{gathered} x^2+7x-3x-21=0 \\ x(x+7)-3(x+7)=0 \\ (x-3)(x+7)=0 \end{gathered}[/tex]
Determine the zeros of the equation
[tex]\begin{gathered} x-3=0\text{ and }x+7=0 \\ x=3\text{ and }-7 \end{gathered}[/tex]
Hence the solution to the given trinomial is 3 and. -7
