Given: (a2+2a+1)x3+(a−1)x2−(a+1)x=0 is an identity.
Thus, the coefficients of x are all equal to 0
⇒a2+2a+1=0⇒(a+1)2=0⇒a=−1⋯(1)
Similarly, a−1=0⇒a=1⋯(2)
And a+1=0⇒a=−1⋯(3)
Thus, from all these equations, we get no unique value of a.
Thus, the number of values of a for which the equation is an identity is 0