(2)an = a 1+(n- 1)d = 3+2n-2 = 2n+ 1 = 2 1n = 10

(3)a6=a 1+5d is 27= 12+5d, so d=3.

④a 1 = a7-6d = 8+2 = 10

3. Let the middle angle be x degrees. Then the other two angles are x-d x+d.

(x-d)+x+(x+d)= 180

X=60 degrees

4.a 1=8.5 a5=- 17.5 So 4d = a5-a1=-26d =-13/2.

a2=a 1+d=8.5- 13/2=2

a4 = a 1+3d = 8.5-39/2 =- 1 1

A8 = a 1+7d = 8.5-9 1/2 =-37

The second question can't be done! I hope it will help you, and I hope you will study hard! These are the foundations!