Question

iii. x2 - 4x -21 = 0​

Answer 1

Answer:

7 or -3

Step-by-step explanation:

Solution:

x^2 -4x -21 =0

or, x^2 -7x +3x -21 =0

or, x(x -7) +3(x -7) =0

or, (x -7) (x +3) =0

Either,

x -7=0

x= 7

Or,

x+3=0

x= -3