Answer:
the common difference is 6.
Step-by-step explanation:
Given;
first term of an AP, a = -7
let the common difference = d
The third term is written as;
T₃ = a + 2d
The eight term is written as;
T₈ = a + 7d
The ratio of the eight term to third term = 7:1
[tex]\frac{T_8}{T_3} = \frac{7}{1} = \frac{a+ 7d}{a + 2d} \\\\7 = \frac{a+ 7d}{a + 2d}\\\\Recall, a = -7\\\\7 = \frac{-7+ 7d}{-7 + 2d}\\\\7(-7 + 2d) = -7+ 7d\\\\-49 + 14d = -7 + 7d\\\\14d -7d = -7 + 49\\\\7d = 42\\\\d = \frac{42}{7} \\\\d = 6[/tex]
Therefore, the common difference is 6.
