Multiply numerator and denominator by the conjugate. Away from zero, the expression becomes √(4x²+9y²+64)+8, whose limit is8+8=16. Defining the origin value as16 makes the function continuous. Therefore D.
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GATE 2020 ST Q36– For f(x,y)=x⁴−2x³y+16y+17 on R², which is true?