Question

-2√7 + 8√28

Answer 1

Its very easy...
first assume x=-2√7 + 8√28
squaring on both sides
x^2=(-2√7 + 8√28)^2
=(-2√7)^2 + (8√28)^2-2(2√7 * 8√28) i.e., (a+b)^2
then solve it....
x^2=4*7+64*28-2*(16*√196)
=4*7+64*28-2(16*14)
=28+1792-448
x ^2 =1372
x=√1372
x=37.04...