(c-3)(c+1)

Apply the distributive property.

c(c+1)-3(c+1)

Apply the distributive property.

c⋅c+c⋅1-3(c+1)

Apply the distributive property.

c⋅c+c⋅1-3c-3⋅1

c⋅c+c⋅1-3c-3⋅1

Simplify each term.

Multiply c by c.

c2+c⋅1-3c-3⋅1

Multiply c by 1.

c2+c-3c-3⋅1

Multiply -3 by 1.

c2+c-3c-3

c2+c-3c-3

Subtract 3c from c.

c2-2c-3

c2-2c-3

Simplify (c-3)(c+1)