Question

If $(a+1/a-3)^2=49$then find $a^2+1/a^2$

• A. 100
• B. 99
• C. 98
• D. 97

Answer 1

Answer:

C. 98

$(a+1/a-3)^2=49$

$a+1/a-3=\sqrt{49}=7$

$a+1/a-3=7$

$a+1/a=7+3=10$

$a^2+1/a^2=10^2-2$

$=100-2=98$

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