For factorizing the algebraic expression 3x²+10x+7, the teacher should help the learner to find two numbers with
Asum 10 and product 7
Bsum 121 and product 10
Csum 10 and product 21
Dsum 7 and product 10
Asum 10 and product 7
Bsum 121 and product 10
Csum 10 and product 21
Dsum 7 and product 10