The common difference of the A.P. b 1, b 2, ldots b m is 2 more than the common difference of A.P. a1, a2, ldots, an If a40=-159, a100=-399 and b100 =a70, then b1 is equal to :

Question

The common difference of the A.P. b 1, b 2, ldots b m is 2 more than the common difference of A.P. a1, a2, ldots, an If a40=-159, a100=-399 and b100 =a70, then b1 is equal to : (A) -127 (B) -81 (C) 81 (D) 127

Tardigrade Admin · Accepted Answer

a1, a2, ldots, an arrow(C D=d) b 1, b 2, ldots, b m arrow( CD = d +2) a40=a+39 d=-159 dots(1) a100=a+99 d=-399 dots(2) Subtract: 60 d =-240 ⇒ d =-4 using equation (1) a+39(-4)=-159 a=156-159=-3 a70=a+69 d=-3+69(-4)=-279=b100 b100=-279 b1+99(d+2)=-279 b1-198 =-279 ⇒ b1=-81

Q. The common difference of the $A . P$ . $b_{1}, b_{2}, \dots$ $b_{m}$ is 2 more than the common difference of $A . P$ . $a_{1}, a_{2}, \dots, a_{n}$ If $a_{40} = - 159, a_{100} = - 399$ and $b_{100}$ $= a_{70},$ then $b_{1}$ is equal to :

$- 127$

$- 81$

$81$

$127$

Q. The common difference of the A.P. b1​,b2​,… bm​ is 2 more than the common difference of A.P. a1​,a2​,…,an​ If a40​=−159,a100​=−399 and b100​ =a70​, then b1​ is equal to :

−127

−81

81

127

Q. The common difference of the $A . P$ . $b_{1}, b_{2}, \dots$ $b_{m}$ is 2 more than the common difference of $A . P$ . $a_{1}, a_{2}, \dots, a_{n}$ If $a_{40} = - 159, a_{100} = - 399$ and $b_{100}$ $= a_{70},$ then $b_{1}$ is equal to :

$- 127$

$- 81$

$81$

$127$