Articles

Arithmetic sequences add the same amount each step; geometric ones multiply. Learn the nth-term and sum formulas with worked examples.

Learn the row-by-column rule, when two matrices can be multiplied, why AB and BA differ, and where matrix products show up in real math.

Hooke’s law says spring force equals stiffness times stretch. Learn F = -kx, how to find k, the energy a spring stores, and where the law stops working.

Momentum is mass times velocity. Learn the formula, units, impulse, and why total momentum stays the same in a collision, with worked examples.

Torque is force times lever arm times the sine of the angle. Learn the formula, the newton meter, wrench math, and how torque turns and balances things.

Linear regression fits the straight line closest to your data. Learn least squares, slope, intercept, R-squared, and when a best-fit line misleads.

Half-life is the time it takes for half of a substance to decay. Learn the formula, what is left after each half-life, and how carbon dating works.

RMDs start at 73. Divide your prior year-end balance by the IRS factor, 26.5 at age 73. See the table, deadlines, and the 25 percent missed-RMD tax.

IRR is the discount rate that makes NPV zero. See how to find it by trial and error, how to read it against your hurdle rate, and when it misleads.

NPV tells you what future cash is worth today, minus the cost. Learn the formula, a worked example, and how the discount rate flips the answer.