Question

बराबर | 12. यदि x=3 + 8 हो, तो +1 होगा (1) 38 (2) 36 (3) 34 (4) 30

11th - 12th Class

Maths

Solution

257

4.0 (1 ratings)

12. (3) दिया गया है कि, ( x=3+sqrt{8} ) ( therefore frac{1}{x}=frac{1}{3+sqrt{8}}=frac{3-sqrt{8}}{(3+sqrt{8})(3-sqrt{8})} ) ( =frac{3-sqrt{8}}{9-8}=3-sqrt{8} ) अब, ( x^{2}+frac{1}{x^{2}}=left(x+frac{1}{x}right)^{2}-2 ) ( =(3+sqrt{8}+3-sqrt{8})^{2}-2 ) ( =36-2=34 )