The diagram shows a right angled triangle. All measurements are given in centimetres.

Show that x2−4x−20=0x^2 - 4x - 20 = 0x2−4x−20=0
Find the value of xxx. Give your answer in the form a±bca \pm b\sqrt{c}a±bc.
Practise AQA GCSE Maths Quadratic Formula with exam-style questions for Foundation and Higher tier. 49 questions, matched to the AQA GCSE Maths (8300) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.