math help best answer and 5 stars?

(1)
△x = [ 3 - (-1) ] / 8 = 0.5
the n-th right endpoint = - 1 + 0.5n ≡ Xn
f( Xn ) = 1 / ( Xn + 3 ) = 1 / ( 0.5n + 2 )

Rn
= Σ [ △x * f( Xn ) ] , from n = 1 to n = 8
= Σ [ 0.5 * f( Xn ) ]
= Σ [ 0.5 / ( 0.5n + 2 ) ] , from n = 1 to n = 8
= 0.5/2.5 + 0.5/3 + 0.5/3.5 + 0.5/4 + 0.5/4.5 + 0.5/5 + 0.5/5.5 + 0.5/6
= 1/5 + 1/6 + 1/7 + 1/8 + 1/9 + 1/10 + 1/11 + 1/12
≒ 1.0199 ..... Ans

(2)
the n-th left endpoint = - 1 + 0.5(n-1) = 0.5n - 1.5 ≡ Xn
f( Xn ) = 1 / ( Xn + 3 ) = 1 / ( 0.5n + 1.5 )

Ln
= Σ [ △x * f( Xn ) ] , from n = 1 to n = 8
= Σ [ 0.5 * f( Xn ) ]
= Σ [ 0.5 / ( 0.5n + 1.5 ) ] , from n = 1 to n = 8
= 0.5/2 + 0.5/2.5 + 0.5/3 + 0.5/3.5 + 0.5/4 + 0.5/4.5 + 0.5/5 + 0.5/5.5
= 1/4 + 1/5 + 1/6 + 1/7 + 1/8 + 1/9 + 1/10 + 1/11
≒ 1.1865 ..... Ans