Question

A student evaluated -4+x for x = -9 1/2and got an answer of 5 1/2? What might th student have done wrong.

Answer 1

Explanation:

Expression evaluated by the student is,

(-4 + x)

For x =
`-9(1)/(2)`

Value of the expression will be,

(-4 + x) =
`-4+(-9(1)/(2))`

=
`-4-9-(1)/(2)`

=
`-13-(1)/(2)`

=
`-13(1)/(2)`

While student evaluated the value of the expression as
`-5(1)/(2)`.

Mistake done by the student may be in the first step
`[-4+(-9(1)/(2))]`.

He might have subtracted
`(-9(1)/(2))` from (-4).