Answers by visitors named: Nerdy...

X,(3x+1), and (7x-4) Soln Arithmetic mean: b=a+c ÷2 b=3x+1, a= x, c=7x-4 3x+1= x + 7x-4/2 Cross multiply 2(3x+1) = ×+7x-4 6x+2 = 8x-4 Collect like terms 6x-8x = -4-2 -2x =-2 Divide through with -2 Therefore x= 1

The others are using the wrong formula to truly find the first three terms of an Ap the arithmetic mean's formula does the job