The value of 3a+b when a=4 and b=-4 is:

1955 AMC 12 Problem 16

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16.

The value of

\dfrac3{a+b}

when

a=4

and

b=-4

is:

3

\dfrac38

0

any finite number

meaningless

Substitute the two given values into the denominator first

A fraction with denominator

0

is undefined

Substitution gives

a+b=4+(-4)=0.

Hence the expression becomes

\frac{3}{0},

which is undefined.

Thus, the expression is meaningless and the correct answer is E.