t4= −5 and t9 = 10. find t1and d. (when i mean t1 and t4, the numbers are small)
t4 = -5
t9 = 10
We have this
t9 = t4 + d ( 9- 4)
10 = -5 + d (5) add -5 to both sides
15 = d (5) divide both sides by 5
3 = d
To find t1 we have
t4 = t1 + d ( 4 - 1)
-5 = t1 + 3 ( 3)
-5 = t1 + 9 subtract 9 from both sides
-14 = t1