Answer:
The common difference is [tex]\frac{1}{2}\quad or\quad 0.5[/tex]
Step-by-step explanation:
[tex]a_n=a_{1}+(n-1)d[/tex]
Using this general equation, we have:
[tex]a_1+(7-1)d-2[a_1+(4-1)d]=1\\\\\mathrm{And:}\\\\a_1+(3-1)d=0[/tex]
Simplify [tex]a_1+(7-1)d-2(a_1+(4-1)d]=1[/tex] to get [tex]a_1=-1[/tex]
and then put in the [tex]a_1+(3-1)d=0[/tex] to get:
[tex]-1+\left(3-1\right)d=0\\\\2d=1\\\\d=\frac{1}{2}[/tex]
Best Regards!
