Like the tenth spatial dimension, the approximate equations in the original five superstring models proved too weak to reveal membranes.

The approximate functional equation gives an estimate for the size of the error term.

A family of approximate equations, "Fowler-Nordheim equations", is named after them.

This is an approximate equation, but holds with good accuracy.

The equation for the redox reaction starting from the pentoxide can be described by this approximate equation:

Below is an approximate equation for calculating the net thrust of a rocket engine:

An approximate equation for the net thrust of a rocket engine is:

The BPM relies on approximate differential equations which are also called the one-way models.

This approximate equation becomes exact when used to define the diffusional mean free path.

A low-specific-thrust engine has a low jet velocity by definition, as the following approximate equation for net thrust implies: