Question

the value of (√5 + √2) (√5-√2) a)10 b) 7
c) 3
d) √3 ​

Answer 1

$answer - 3$

Procedure

• use (a+b)(a-b) formula

in this question formula (a+b)(a-b) can be applied

which gives

$(a + b)(a - b) = {a}^{2} - {b}^{2}$

hence answer comes out to be

$( { \sqrt{5} })^{2} - ({ \sqrt{2} )}^{2} = 5 - 2\rightrightarrows3$

Additional information

$({a + b})^{2} = {a}^{2} + {b}^{2} + 2ab$

$({a - b})^{2} = {a}^{2} + {b}^{2} - 2ab$