Substitution: Is 3b² 12 or 36 When b = −2? | GCSE Maths

Substitution for GCSE Maths: putting numbers, including negatives, into expressions and formulae. With a = 3 and b = −2: 4a − 5b, a²b, and the four that cost the most marks: 3b², (3b)², −b² and (−b)². Formulae from science given in the question (v = u + at, s = ut + ½at², F = 9C/5 + 32), a fraction where the line works like a bracket, and why a calculator needs brackets round a negative. Plus the mistakes that cost marks. Foundation and Higher. Covers: AQA 8300 3.2.1 A2 · Edexcel 1MA1 Topic 2 A2 · OCR J560 6.02b (Foundation and Higher on all three). 0:00 Intro 0:08 Hook 0:35 Substituting, with negatives 1:07 Squares and minus signs 1:49 Formulae from other subjects 2:51 Fractions 3:21 On a calculator 3:45 Common mistakes 4:11 Summary Narrated with an AI voice. Worked Example is not affiliated with or endorsed by AQA, OCR or Pearson Edexcel. Exam board names are used only to show which specifications a video covers.