Using the "complete the square" method, solve the following x^2 +4x - 21 =0
x2+4x-21= 0, This can be factorised into brackets as shown: (x+2)2 - 4 - 21 = 0 SImplified, so all x's are on one side of the equation: (x+2)2 = 25, Removing square root, DONT FORGET "±" : (x+2) = ± 5, Solve for two solutions: x = 3, x = -7
CS
Related Maths A Level answers
All answers ▸Integrate xsin(2x) by dx between the limits 0 and pi/2.
What is the chain rule and how does it work?
The function f(x) is defined by f(x) = 1 + 2 sin (3x), − π/ 6 ≤ x ≤ π/ 6 . You are given that this function has an inverse, f^ −1 (x). Find f^ −1 (x) and its domain
Find the total area enclosed between y = x^3 - x, the x axis and the lines x = 1 and x= -1 . (Why do i get 0 as an answer?)