Solving Equations

Instacalc solves equations for you — linear, quadratic, and beyond.

Solve for a variable

Write solve in front of an equation. When an equation has several solutions, Instacalc returns all of them — click Show steps to see the work.

Trig equations return the general solution — n stands for any integer, so the answer covers every angle that works:

Polynomial roots

roots gives the roots of a polynomial directly:

The roots are where the curve crosses zero — plot it over a tight window to see them (the parabola dips below the x-axis and crosses it at 2 and 3):

Reverse a formula (goal-seek)

You can also work backwards from an answer. Put solve in front of an equation that sets a formula equal to the target you want, and Instacalc finds the input:

The same numeric goal-seek powers the solve affordance in the calc UI — set the result you want on any row and Instacalc finds the input that produces it.

Choose which inputs to change

When a formula has several inputs, add using to say which one to solve for — and hold the others fixed by giving them a value:

A bare name (cost) is the unknown Instacalc solves for; a name with a value (budget = 45) is held fixed. So this reads “with the budget at 45, what cost leaves 440?” List several bare names to vary them together.

See also

• Calculus — derivatives, integrals, limits
• Science & Engineering — note: trig defaults to degrees
• Reference — full function list