Quantitative aptitude

pl solve those problems.

sign used in your problem is not proper, so you can post scanned copy of your querry.

there is no wrong in sign of problems.please solve this.g^2 means g square.

for 2. 

1/(g^2-a^2) + 1/(g^2-b^2)

=1/(g^2-g^4/b^2) + 1/(g^2-b^2)  ( gis G.M., so,g^2=ab, g^4=a^2b^2,so a^2=g^4/b^2..in this step we have substituted a^2)

=b^2/(g^2 b^2-g^4) + 1/(g^2-b^2)(by solving the denominator,b^2 goes to the numerator)

=b^2/-g^2(g^2-b^2) + 1/(g^2-b^2)( -b square is taken out commen in denominator).

=(b^2-g^2)/-g^2(g^2-b^2) ((taking (g^2-b^2) as LCM and solving the fraction ))

=1/g^2  (( in the numerator we take out  (-) sign common so,  (g^2-b^2)gets cancelled ))

=1/g^2