a) √50 = √(25 x 2) =√(5² x 2) = 5√2, what Jacklyn did is the other way round, instead of putting the perfect square out of the radical & keep the 2 inside, she inversed the sens of the operation
b) We have to find the square of the smaller & largest numbers that are near 50:
7² = 49 & 8² = 64==> so 49<50<64 & the number is between the square root of 7 & the square root of 8, but we also notice that 50 is very very near 49, hence let's try 7.1==> 7² = 7.1 x 7.1 = 50.41, which is a very good approximation. Then the approx. to √50 ≈ 50.41