Question

If a=3+2√2, find the value of a²+1/a². will mark brainliest for the best answer!! -class 9 cbse

Answer 1

$a = 3 + 2 \sqrt{2} \\ \frac{1}{a} = \frac{1}{3 + 2 \sqrt{2} } \\ rationalise \: \frac{1}{a} \\ \frac{1}{3 + 2 \sqrt{2} } \times \frac{3 - 2 \sqrt{2} }{3 - 2 \sqrt{2} } \\ = \frac{3 - 2 \sqrt{2} }{ {(3)}^{2} - {(2 \sqrt{2}) }^{2} } \\ = \frac{3 - 2 \sqrt{2} }{3 - (4 \times 2) } \\ = \frac{3 - 2 \sqrt{2} }{3 - 8} \\ \frac{3 - 2 \sqrt{2} }{ - 5}$