I need help with some algebra problems

Question

14. Factor 3a^2 5ab-12b^2

18. Factor 3x^2 5xy-12y^2

20. Factor 21x^2 58xy 21y^2

35. Factor x^2 10x 25 – y^2

Answer 1

Yahoo! Answers has been removing the plus signs from questions lately (but not from answers or edits to the questions.  So, I'm going to assume the problems are:

Factor 3a^2+ 5ab-12b^2

Factor 3x^2+ 5xy-12y^2

Factor 21x^2+ 58xy+ 21y^2

Factor x^2 +10x+ 25 – y^2

14: (3a-4b)(a+3b)

18: (3x-4y)(x+3y)

20:

This one doesn't factor well unless it's 21x^2+58xy-21y^2, in which case it factors to

(21x-7y)(x+3y)

35

[(x+5)+y][(x+5)-y]

_/