Question Number 10339 by konen last updated on 04/Feb/17

A=1×2 + 2×3 +3×4+...+10×11  B=3×8 +6×12 +9×16+...+30×44  ⇒(A/B)=?

Answered by mrW1 last updated on 04/Feb/17

a_n =n×(n+1)  b_n =3×n×4×(n+1)=12×n×(n+1)=12a_n   A=Σ_(n=1) ^(10) a_n   B=Σ_(n=1) ^(10) b_n =12Σ_(n=1) ^(10) a_n =12A  ⇒ (A/B)=(A/(12A))=(1/(12))

Answered by arge last updated on 05/Feb/17

  A,  n=10, d=4  a_1 =2  a_2 =6  a_(10) =110    S_n =(((a_n −a_1 +d)(a_1 +a_n ))/(2d))    S_n A=1568    B, n=? , d=48  a_1 =24  a_2 =72  a_n =1320    n=((a_n −a_1 )/d) +1=28    S_n B=32256      A/B=(7/(144))

Commented bymrW1 last updated on 05/Feb/17

I don′t think this is correct, sir. Both  A and B are not A.P.!

Commented byarge last updated on 05/Feb/17

    La calculadora que ofrecio los datos para el lanzamiento del transbordador espacial en USA, fallo y ocurrio el accidente.

Commented bymrW1 last updated on 06/Feb/17

can you please translate into english?