Question

under root 21 minus 4 root 5 + 8 root 3 minus 4 root 15 equals to?

Answer 1

Answer:

The value of the given expression is $\sqrt{21-4\sqrt{5}+8\sqrt{3}-4\sqrt{15}}=3.228$

Step-by-step explanation:

Given : Expression 'under root 21 minus 4 root 5 + 8 root 3 minus 4 root 15'.

To find : The given expression is equal to?

Solution :

First we write the expression in mathematical form

'under root 21 minus 4 root 5 + 8 root 3 minus 4 root 15'.

i.e. $x=\sqrt{21-4\sqrt{5}+8\sqrt{3}-4\sqrt{15}}$

We substitute the value of each root using calculator,

$x=\sqrt{21-4(2.236)+8(1.732)-4(3.872)}$

$x=\sqrt{21-8.944+13.856-15.491}$

$x=\sqrt{10.420}$

$x=3.228$

Therefore, The value of the given expression is $\sqrt{21-4\sqrt{5}+8\sqrt{3}-4\sqrt{15}}=3.228$