Substituting into a Formula Without Bracket Mistakes

Updated Aug 24, 2026 · View standard page

Take the formula:

y = 2x^2 − 3x + 1

If x = −2, write:

y = 2(−2)^2 − 3(−2) + 1

Now evaluate:

y = 2(4) + 6 + 1 = 15

Why the brackets matter

Without brackets, it is easy to read −3x as −3 × 2 instead of −3 × (−2). The brackets keep the sign attached to the substituted number.

Habit worth keeping: substitute first, then simplify. Do not try to do both in one jump.