Answer:
(x+3) (x+5)
Explanation:
1) When factorising a quadratic like this the first step is to put x in front of two brackets:
(x ) (x )
2) Next check if all numbers in your question is positive (+). In this case it is so we put + after both x in bracket.
(x+ ) (x+ )
3) now the last number in your question is 15 so we find all factors of 15:
1 and 15
3 and 5
4) to know which pair of factors to use we look at owr second number in the question which is 8x. The factors that add up to 8 is 3 and 5.
Voilà