Question

To rationalize the denominator of 1/2 +root 5 we should multiply numerator and denominator by : (a) 2 (b) 2-root 5 (c) root 5 (d) 2+ root 5

Answer 1

option (b) is correct

Step-by-step explanation:

To rationalize we always multiply and divide by a number which has apposite sign than that of under root term

Here we have $\frac{1}{2+root5}$ , positive sign between the number and root term, so we have to multiply and divide by the negative sign between them or by $(2-root5)$ to rationalize this number.

such that,

=$\frac{1\times(2-root5) }{(2+root5)(2-root5)}$

=$\frac{(2-root5) }{-3}$ will be answer.

Answer 2

The correct answer is b) 2-root5