Which of the equations are true identities?
\begin{aligned} \text{A. }&(5b-2)^2+4=25b^2-20b \\\\ \text{B. }&(2x^2+y^2)(2x^2-y^2)=4x^2-y^2 \end{aligned}
A.
B.
​

(5b−2)
2
+4=25b
2
−20b
(2x
2
+y
2
)(2x
2
−y
2
)=4x
2
−y
2

​