Question 812049
What is the exact value of the expression the square root of 9 times y to the fourth power. + 12the square root of y to the sixth power. − 3the square root of y to the sixth power. − the square root of y to the fourth power.? Simplify if possible. 
:
{{{sqrt(9y^4) + 12sqrt(y^6) - 3sqrt(y^6) - sqrt(y^4)}}}
in the first radical we can extract the square root of 9
{{{3sqrt(y^4) + 12sqrt(y^6) - 3sqrt(y^6) - sqrt(y^4)}}}
Group like terms and just do the math
{{{3sqrt(y^4) - sqrt(y^4)}}} + {{{12sqrt(y^6) - 3sqrt(y^6)}}}
Which is
{{{2sqrt(y^4)}}} + {{{9sqrt(y^6)}}}
Extract those square roots
{{{2*y^2}}} + {{{9*y^3}}}