A sequence is given by Un=a(1-2n).determine the first 3 term of sequence

just plug in n=1,2,3:

a(1-2) = -a
a(1-4) = -3a
a(1-6) = -5a

To determine the first three terms of the sequence with the given equation U_n = a(1-2n), we need to substitute the values of n from 1 to 3 into the equation and calculate the corresponding terms.

Let's start by substituting n = 1 into the equation:
U_1 = a(1 - 2(1))
= a(1 - 2)
= a(-1)
= -a

The first term of the sequence is -a.

Now, let's substitute n = 2 into the equation:
U_2 = a(1 - 2(2))
= a(1 - 4)
= a(-3)
= -3a

The second term of the sequence is -3a.

Finally, let's substitute n = 3 into the equation:
U_3 = a(1 - 2(3))
= a(1 - 6)
= a(-5)
= -5a

The third term of the sequence is -5a.

Therefore, the first three terms of the sequence are -a, -3a, and -5a.