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 ▸The probability function of a discrete random variable X is given by p(x)=x^2 x =1,2,3. Find E(X)
Integrate by parts the following function: ln(x)/x^3
Prove that 2Sec(x)Cot(x) is identical to 2Cosec(x)
How do I solve equations with modulus functions on both sides?