Answer:
x^2 - 13x + 36
Explanation:
Use the so-called FOIL method: multiply First terms, Outer terms, Inner terms, Last terms.
First terms: (x)(x) = x^2
Outer terms: (x)(-9) = -9x
Inner terms: (-4)(x) = -4x
Last terms: (-9)(-4) = 36
Combining the x terms, we get
x^2 - 13x + 36