(Solved): A sample of 5 positive numbers, each less than 30 , are rounded to the first decimal place and then ...

A sample of 5 positive numbers, each less than 30 , are rounded to the first decimal place and then their squares are added together. Estimate the maximum possible error in the computed answer that might result from the rounding. The estimate of the maximum error is: (1 poinc) Find an equation of the tangent plane to the surface $$z=?2\ln (2x+y)$$ at the point $$(2,?3,0)$$.