(3a+4b)^2=9a^2+16b^2+24a*b
=81+256+24*3*4*(-1/2)
=193,
∴|3a+4b|=√193.
(3a-4b)^2=9a^2+16b^2-24a*b
=81+256-24*3*4*(-1/2)
=481,
∴|3a-4b|=√481.
(3a+4b)^2=9a^2+16b^2+24a*b
=81+256+24*3*4*(-1/2)
=193,
∴|3a+4b|=√193.
(3a-4b)^2=9a^2+16b^2-24a*b
=81+256-24*3*4*(-1/2)
=481,
∴|3a-4b|=√481.