Answer:
[tex]a_{8} = 15[/tex]
Step-by-step explanation:
[tex]a_{1} + a_{2} + ..... + a_{7} + a_{8} = 8^{2} = 64[/tex]
[tex]-a_{1} - a_{2} ..... - a_{7} = - 7^{2} = -49[/tex] Now add the two equations
[tex]a_{8} = 64 - 49 = 15[/tex]
[tex]a_{8} = 15[/tex]
