Question

factorise x²-3√5x-20

Answer 1

Hey!!!..Here is ur answer

${x}^{2} - 4 \sqrt{5}x + \sqrt{5} x - 20 \\ \\ x(x - 4 \sqrt{5} ) + \sqrt{5} (x - 4 \sqrt{5} ) \\ \\ (x - 4 \sqrt{5} )(x + \sqrt{5} )$

Hope it will help you

Answer 2

This sum is solved by sum and product method
X^2-3\/5x-20
The sum of - 4\/5x+1\/5x=-3\/5x
The product of - 4\/5x*1\/5x= 20*x^2=20x^2
So,
X^2 +\/5x-4\/5x-20
X(x+\/5)-4\/5(x+\/5)
[taking commonly out]
(x+\/5)(x-4\/5)
(OR)

[Multiple of - 20*x^2 is - 4 root 5 x and +1 root 5 x and it's sum also gives - 3 root 5 x]

x^2-3 root 5 x-20
X^2+ root 5 x - 4 root 5 x - 20
x(x+root 5)-4 root 5(x+root 5)
(x-4 root 5)(x+root 5)