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### Question

If $√5$ = 2.24, then what is the value of ${√5}/2$ − $3/{√5}$ + $√20$?

**A**

4.249.

**B**

4.449.

**C**

4.649.

**D**

4.496.

**Soln.**

**Ans: a**

The given expression can be simplified to ${{(√5)^2} - {2 × 3} + {2 × √5 × √{5 × 2^2}}}/{2 × √5}$, which is same as ${5 - 6 + 20}/{2 × √5}$, which is same as ${19/{2 × √5}$. Rationalizing, we get ${19/{2 × √5} × {√5/√5}$ which gives ${19√5}/10$ which = 4.249.