math
posted by rick on .
Factor each of the following trinomials: (14 marks)
A)15s2 + 26s + 8
B) x4 – 5x2 – 36 (hint: let a = x2)
C) t2 + 4t – 2
D) 2w2 – w – 4

A) You know it will be one of
(5s+a)(3s+b)
(15s+a)(s+b)
where a*b = 8
Looks like 15,1 won't work, so
(3s+4)(5s+2)
wolframalpha will do polynomial factorization, but the only way you'll be ready for a test is to do lots of these. It's just trial and error until you have enough practice to factor by inspection.