Question

If $(a+1/a-3)^2=25$then find $a^2+1/a^2$

• A. 36
• B. 66
• C. 64
• D. 62

Answer 1

Answer:

D. 62

$(a+1/a-3)^2=25$

$a+1/a-3=\sqrt{25}=5$

$a+1/a-3=5$

$a+1/a=5+3=8$

$a^2+1/a^2=8^2-2$

$=64-2=62$

if $a+1/a=k$ then $a^2+1/a^2=k^2-2$