Answer:
Option (b) is correct.
The solution of the quadratic equation [tex]x^2+4x=21[/tex] is -7 and 3
Step-by-step explanation:
Consider the given quadratic equation [tex]x^2+4x=21[/tex]
This can be rewritten as, [tex]x^2+4x-21=0[/tex]
We can solve the quadratic equation using middle term splitting method,
4x can be written as 7x-3x , we get,
[tex]\Rightarrow x^2+4x-21=0[/tex]
[tex]\Rightarrow x^2+7x-3x-21=0[/tex]
Taking terms common, we get,
[tex]\Rightarrow x(x+7)-3(x+7)=0[/tex]
Thus, [tex]\Rightarrow (x-3)(x+7)=0[/tex]
Thus, we get (x-3)= 0 or (x+7)= 0
this gives x = 3 or x = -7
Thus, the solution of the quadratic equation [tex]x^2+4x=21[/tex] is -7 and 3
