1. The problem statement, all variables and given/known data 30(a^2+b^2+c^2+d^2)+68ab-75ac-156ad-61bc-100bd+87cd 2. Relevant equations 3. The attempt at a solution I've tried the form (Aa+Bb+Cc)(Da+Eb+Fc) expand this and equate to the orig expression I ended up getting (5a+3b-5c)(6a+10b-6c) which when I expand does not give me a correct similar expression. I need help on this.