Vedic maths · trick 34 of 36 · free

Simultaneous equations — Vedic maths trick

Two equations, two unknowns. A cross-multiplication pattern gives x and y directly, and when the numbers swap places the sutra “by addition and by subtraction” (Sankalana-Vyavakalanabhyam) is even faster.

The trick

Paravartya Yojayet — “transpose and apply”

  1. For ax + by = c and dx + ey = f: bottom = a×e − b×d.
  2. x = (c×e − b×f) ÷ bottom; y = (a×f − c×d) ÷ bottom.
  3. Special case ax + by = c, bx + ay = f: add the equations to get x + y, subtract to get x − y, then add and halve.
  4. Check your x and y in the first equation.

Use it for: Linear equations in two variables (Class 8–10). Type the answer as x and y in the two boxes.

Worked example: 2x + 3y = 13 and 5x − y = 7 → x = 2, y = 3

  1. Bottom: 2 × (−1) − 3 × 5 = −17.
  2. x = (13 × (−1) − 3 × 7) ÷ (−17) = −34 ÷ (−17) = 2.
  3. y = (2 × 7 − 13 × 5) ÷ (−17) = −51 ÷ (−17) = 3.
  4. Answer: x = 2, y = 3.

Check: 2 × 2 + 3 × 3 = 13 and 5 × 2 − 3 = 7 ✓

✏️ Practice

Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.

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🏁 Trick 34 test

20 sums. Check each answer, then go to the next one. Get 16 or more right to pass.

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🖨️ Simultaneous Equations Worksheet

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