GCSE The Quadratic Formula Dr J Frost jfrosttiffin
- Slides: 8
GCSE: The Quadratic Formula Dr J Frost (jfrost@tiffin. kingston. sch. uk) Last modified: 27 th June 2018
Introduction Try to solve the following by factorising. What problem do you encounter? There are no two integers numbers which add to give 2 and ? multiply to give -5. We therefore can’t factorise. ? Is there a quick way of solving non-factorisable equations without having to complete the square each time?
Solving more generally Note: You are not expected to reproduce this proof in an exam. ? ? ? It effectively gives us a way of solving by completing the square, but where the algebra has already been done for us.
The Quadratic Formula Fro Tip #1: Notice that we need 0 on the RHS. ? ? Fro Tip #2: You know you won’t be able to factorise if a GCSE question ends with “to 3 sf” or “to 2 dp”.
Test Your Understanding Equation Solutions (to 3 sf) ? ? ? ? ? ? ? No solutions. ?
“Show that” questions a ? b ?
Exercises 1 Solve the following, giving your answers correct to 3 significant figures. a ? b ? c d e f ? ? ? 3 ? N 1 ? ? ? ? g ? h i 2 ? N 2 ?
Final Test Your Understanding Q ? ?
