Equation Solver f(x)=0 Calculator

Find the real roots of f(x) = 0 inside a search range you choose.

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What it asks for

The formula

Step 1: check f(a) ร— f(b) < 0
Step 2: midpoint m = (a + b) / 2
Step 3: if f(a) ร— f(m) < 0 the root is in [a, m], so replace b with m; otherwise replace a with m
Step 4: repeat. After n steps the interval width is (b โˆ’ a) / 2โฟ

From the article Solving f(x) = 0 Numerically โ€” Bisection and Newton's Method.

Worked example

Take f(x) = xยณ โˆ’ x โˆ’ 2 on the interval [1, 2].

f(1) = 1 โˆ’ 1 โˆ’ 2 = โˆ’2 (negative)
f(2) = 8 โˆ’ 2 โˆ’ 2 = +4 (positive)
Signs are opposite, so a root lies between 1 and 2.

After five steps the root is trapped between 1.5 and 1.53125. The true root is 1.5214 (to 4 decimals). Notice the pattern: every step halves the uncertainty, and nothing can go wrong.

Worked in full in Solving f(x) = 0 Numerically โ€” Bisection and Newton's Method.

Learn the method

About this tool

This is one of the tools in the Chemistry Calculator Suite, a free calculator built for IIT-JAM, CSIR-NET, GATE and CUET (Chemical Science) preparation. Nothing is behind a login and no result is stored on a server — the arithmetic runs in your own browser.

The Equation Solver f(x)=0 calculator above is the live tool — type your values and press its button; the answer appears in the same box. The link under it opens the full suite with this tool already selected, next to the others.

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