Question

Find the 7th term of the arithmetic sequence 5x + 9, 8x + 5, 11x + 1,...

Answer 1

Answer:

          $\bold{a_7=33x-15}$

Step-by-step explanation:

In arithmetic sequence:  a₂ - a₁ = a₃ - a₂     {common difference}

$a_1=5x+9\\a_2=8x+5\\a_3=11x+1\\\\\\d=8x+5-(5x+9)=8x+5-5x-9=3x-4\\\\a_n=a_1+d(n-1)\\\\a_7=5x+9+(3x-4)\cdot6\\\\a_7=5x+9+18x-24\\\\a_7=33x-15$