Viết các biểu thức sau dưới dạng tổng:
a)\(\left(a-b^2\right)\left(a+b^2\right)\) c)\(\left(a^2+2a+3\right)\left(a^2-2a-3\right)\)
b)\(\left(a^2+2a+3\right)\left(a^2+2a-3\right)\) d)\(\left(a^2-2a+3\right)\left(a^2+2a-3\right)\)
e)\(\left(-a^2-2a+3\right)\left(-a^2-2a+3\right)\) f)\(\left(a^2+2a+3\right)\left(a^2-2a+3\right)\)
g)\(\left(a^2+2a\right)\left(2a-a^2\right)\)
a: \(=a^2-b^4\)
b: \(=\left(a^2+2a\right)^2-9\)
c: \(=a^2-\left(2a+3\right)^2\)
d: \(=a^4-\left(2a-3\right)^2\)
e: \(=\left(-a^2-2a+3\right)^2\)
g: \(=4a^2-a^4\)