Question

or the 34-64 127 5.) Write the explicit formula for the arithmetic sequence. -18, -7, 4, 15, 26,... -21,-10,7,18,29

Answer 1

we have the sequence

-108, -91,-74,-57,...

we have

a1=-108

a2=-91

a3=-74

a4=-57

step 1

Find the common difference d

a2-a1=-91-(-108)=17

a3-a2=-74-(-91)=17

so

d=17

step 2

thw general equation for an arithmetic sequence is equal to

an=a1+d(n-1)

we have

d=17

a1=-108

substitute

an=-108+17(n-1)

an=-108+17n-17

an=-125+17n

therefore

the answer is an=-125+17n