Solve x^2+8x-5 = 0 by completing the square.
x2 + 8x = (x + 4)2 - 16, so x2 + 8x - 5 = (x + 4)2 - 16 - 5 = (x + 4)2 - 21, so then (x + 4)2 - 21 = 0 (x + 4)2 = 21 -----> x + 4 = √21 -------> x = -4 + √21 x = -4 - √21
SJ
Related Maths GCSE answers
All answers ▸How do I calculate a percentage increase? For example; there are 15 fish in a fish tank, after a year they have bred and now there are 20 fish in the tank. By what % has the number of fish increased?
Daniel bakes 420 cakes. He bakes only vanilla cakes, banana cakes, lemon cakes and chocolate cakes. 72 of the cakes are vanilla cakes. 35% of the cakes are banana cakes. The ratio of the number of lemon cakes to the number of chocolate cakes is 4:5 Work
How to find the exact formula of the function if the graph of it is given?
Express 56 as a product of its prime factors