Core formulas

A concise glossary section with core algebra, geometry, and physics formulas for students in Grades 8–11.

How to use formulas

A formula is useful only when you understand when it applies. Before substituting values, identify the quantities and convert all units to a consistent system.

Quadratic equation

D = b² − 4ac;x = (−b ± √D) / 2a

For the equation ax² + bx + c = 0, where a ≠ 0.

Linear function

y = kx + b

k defines the slope of the line, and b is its y-intercept.

Pythagorean theorem

a² + b² = c²

For a right triangle, where c is the hypotenuse.

Uniform motion

v = s / t

Speed equals distance divided by time.

Newton's second law

F = ma

Force equals mass multiplied by acceleration.

Ohm's law

I = U / R

Current depends on the voltage and resistance of the circuit section.

Check before answering

are all quantities written in compatible units;
have all restrictions and domain conditions been considered;
does the answer make sense in the context of the problem.

Discuss the goal and lesson format

Send me the student's grade, subject, preparation goal, and convenient time on Telegram or Instagram. I will reply and explain the next step.