Please help me is about polynomials

(x + 3)(x² – 3x + 7)

Step-by-step explanation:

To express x³ + 2x + 21 in the form of (x + 3)(px² + qx + r),

we need to divide (x³ + 2x + 21) by

(x + 3), since (x + 3) is a factor of

(x³ + 2x + 21)

See attached photo on how to divide (x³ + 2x + 21) by (x + 3).

From the attached photo,

(x³ + 2x + 21)/ (x + 3) = x² – 3x + 7

Therefore,

x³ + 2x + 21 => (x + 3)(px² + qx + r)

x³ + 2x + 21 => (x + 3)(x² – 3x + 7)