Question

U3=-50, u20= 18
1. deduce the common difference
write the term to term rule

Answer 1

Answer:

U3=-50 | U20=18

U+(3-1)d=-50 |. U+(20-1)d=18

U+2d=-50 (1st equation) |. U+19d=18(2 equa)

+U+2d=-50. (U will cut with U)

+U+19d=+18. (U will cut with U )

- - = -

_______________

-17d=-32

_______________

D =-32/-17

D =32/17

D put in 1st equation

U+2d=-50

U+2(32/17)=50

U =50 -64/17

U= 850-64÷17

U= 786÷17

U=17.4