Adding and subtracting polynomials
The question
(x + 9)(x + 1)
Write the answer as a polynomial.
(x + 9)(x + 1)
(x + 9)(x + 1)
x²+x
+9x+9
x + 9x = 10x
=x² + 10x + 9
- Every term in the first bracket multiplies every term in the second — four multiplications.
- x × x = x², and x × 1 = x.
- Then the other one: 9 × x = 9x, and 9 × 1 = 9.
- Two of those four are x terms, so they collect: x + 9x = 10x. The answer is x² + 10x + 9.
How it works.
- 01
Every term in the first bracket multiplies every term in the second — four multiplications.
- 02
x × x = x², and x × 1 = x.
- 03
Then the other one: 9 × x = 9x, and 9 × 1 = 9.
- 04
Two of those four are x terms, so they collect: x + 9x = 10x. The answer is x² + 10x + 9.