Write the equation of the plane tangent to the graph of the function given by z = f(x; y) = ln(x^2 + y^2 +1)

As soon as look at the parallelogram abcd shown below: the table below shows the steps to prove that if the quadrilateral abcd is a parallelogram, then its opposite sides are congruent: which choice completes the missing information for reason 5 in the chart? (6 points) congruent parallelograms congruent triangles similar angles similar triangles

Can someone me out here number 4 plz

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?