volume_mute
Solve: (a + 4)(a + 9)
publish date: 2020/12/29 00:45:00 GMT+11
volume_mute
Correct Answer
\(a^2+13a+36\)
Explanation
Apply FOIL method = (
\[
a+b)(c+d)= ac+ad+bc+bd
a= a, b=4, c=a, d=9
=aa+ax9+4a+4x9= a^2+13a+36
\]
Reference
Mathematics for college students