Giúp với ạ

Giúp gấp với

1) 3x⁴-11x²+10=0

Đặt x²=t \(\left(t\ge0\right)\rightarrow x^4=t\)

Ta có PT: 3t²-11t+10=0 (a=3;b=-11;c=10)

\(\Delta=b^2-4ac=\left(-11\right)^2-4.3.10=1\\ \rightarrow t_1=\dfrac{-b+\sqrt{\Delta}}{2a}=\dfrac{-\left(-11\right)+\sqrt{1}}{2.3}=2\left(t/m\right)\rightarrow x_1=\pm\sqrt{2}\\ \rightarrow t_2=\dfrac{-b-\sqrt{\Delta}}{2a}=\dfrac{-\left(-11\right)-\sqrt{1}}{2.3}=\dfrac{5}{3}\left(t/m\right)\rightarrow x_2=\pm\dfrac{\sqrt{15}}{3}\\ \rightarrow S=\left\{\sqrt{2};-\sqrt{2};\dfrac{\sqrt{15}}{3};-\dfrac{\sqrt{15}}{3}\right\}\)

How old do you think this building is ?

A.When did you build this building ?

B.How many buildings did you build ?

C.How old were you when you built this building ?

D. When was this building built ?