Simplify the following surds :
1) 2√21 × √27 ÷ √343
2) 7√5 × √125 ÷ 2√27

1)

2)

Step-by-step explanation:

* Lets explain how to simplify a square root

1)

∵ × ÷

∵ ×

∴ = ×

∵ = × ×

∵ × = 3

∴ =

∴ × =

  × ×

∵ × = 3

∵ 2 × 3 × 3 = 18

∴ × =

∵ = × ×

∵ × = 7

∴ =

∵ × ÷ =

  ÷

∵ ÷ = 1

∴ × ÷ =

2)

∵ × ÷  

∵ = × ×

∵ × = 5

∴ =

∴ × =

  ×

∵ × = 5

∴ × = 7 × 5 × 5 = 175

∵ = × ×

∵ × = 3

∴ =

∴ × ÷ =

  175 ÷ =

∵ not in the simplest form because

  the denominator has square root

∴ Multiply up and down by

∴   =

∴   =

∴ × ÷ =

the answer will be b x² +x-1

step-by-step explanation: