Question

Please help me solving this

Answer 1

12√18-6√20-3√50+8√45
= 36√2-12√5-15√2+24√5
= 3( 12√2-4√5-5√2+8√5)
= 3( 12√2-5√2-4√5+8√5)
= 3( 7√2+4√5)
= 21√2 + 12√5