Question

If a2+9/a2=31,what is the value of a-3/a

Answer 1

a²+9/a²=31   (i)

Following identity
(a+b)²=a²+b²+2ab
putting(i)
(a-3/a)²=a²+9/a²+2(a)(-3/a)
(a-3/a)²=31+(-6)
(a-3/a)²=25
(a-3/a)=5

Answer 2

a-3/a = 5

Step-by-step explanation:

(a -3/a) ^2 = a2 - 2 × a × 3/a + (3/a)

=( a+b)2

= a2 - 2ab +b2

= a2 - 6 + 9/a2

= ( a - 3/a)2 = 25

= a - 3/a = 5

Hope it helps u!! .................