# GATE2018-43

If $1+r + r^2+ r^3 +\dots \infty = 1.5$, then, $1 + 2r + 3r^2 + 4r^3 + \dots \infty =$ (up to two dcimal places) ________
in Calculus
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## Related questions

1
An infinite series $S$ is given as: $S=1+2/3+3/9+4/27+5/81+\:.\dots$ (to infinity) The value of $S$ is ______________________ (round off to $2$ decimal places).
2
Consider the following infinite series: $1+ r+r^2 +r^3+ \dots \dots \infty$ If $r = 0.3$, then the sum of this infinite series is ____________
Which of the following are geometric series? $1,\:6,\:11,\:16,\:21,\:26,\:\dots$ $9,\:6,\:3,\:0,\:-3,\:-6,\:\dots$ $1,\:3,\:9,\:27,\:81,\:\dots$ $4,\:-8,\:16,\:-32,\:64,\:\dots$ $P$ and $Q$ only $R$ and $S$ only $Q$ and $S$ only $P, Q$ and $R$ only
The sum of the infinite geometric series $1 + 1/3 + 1/3^2+ 1/3^3+ \dots$ (rounded off to one decimal place) is ___________
Calculate the following integral (up to two decimal places) $\displaystyle \int_0^1 (x + 3)(x + 1)dx = \text{ ___________}$