Question

x^2-3root5x-20 factorise

Answer 1

Answer:

${x}^{2} - 3 \sqrt{5}x - 20 \\ d = {b}^{2} - 4ac \\ ( - 3 \sqrt{5}) {}^{2} - 4(1)( - 20) \\ 45 + 80 \\ 125 = d \\ x = \frac{ - b + \sqrt{d} }{2a} \\x = \frac{ - ( - 3 \sqrt{5}) + \sqrt{125} }{2} \\ x = \frac{3 \sqrt{5} + \sqrt{125} }{2} \\ x = \frac{3 \sqrt{5} + 5 \sqrt{5} }{2} \\x = \frac{8 \sqrt{5} }{2} \\ x = 4 \sqrt{5} = answer \\ \\ x = \frac{ - b - \sqrt{d} }{2a} \\ x = \frac{ - ( - 3 \sqrt{5}) - \sqrt{125} }{2} \\ x = \frac{3 \sqrt{5} - \sqrt{125} }{2} \\ x = \frac{3 \sqrt{5} - 5 \sqrt{5} }{2} \\ x = \frac{ - 2 \sqrt{5} }{2} \\ x = - \sqrt{5} = answer$

Answer 2

Here is your answer mate.