Question

Write first four terms of the AP,when the first term a and the common difference d are given as follows:
(i) a=10 , d=10
(ii) a=-2, d=0
(iii) a=4 , d=-3
(iv) a=-1 , $d=\frac{1}{2}$
(v) a=-1.25 , d=-0.25

Answer 1

a = first term

d = difference

n = nth term

(1) $a=10;d=10$

$\Rightarrow 10;a+d;a+2d;a+3d$

$\Rightarrow 10;10+10;10+20;10+30$

$\Rightarrow 10;20;30;40$

(2) $a=-2;d=0$

$\Rightarrow a;a+d;a+2d;a+3d$

$\Rightarrow -2,-2+0;-2+0;-2+0$

$\Rightarrow -2,-2,-2,-2$

(3) $a=4,d=-3$

$\Rightarrow a,a+d;a+2d;a+3d$

$\Rightarrow 4,4-3;4-6;4-9$

$\Rightarrow 4,+1;-2,-5$

(4) $a=-1;d=\frac{1}{2}$

$\Rightarrow a;a+d;a+2d;a+3d$

$\Rightarrow -1;-1+\frac{1}{2};a+2\cdot \frac{1}{2};a+3\cdot \frac{1}{2}$

$=-1,-\frac{1}{2};0;\frac{1}{2}$

(5) $a=-1.25;d=-0.25$

$\Rightarrow a;a+d;a+2d;a+3d$

$\Rightarrow -1.25;-1.25-0.25;-1.25-0.5;-1.25-0.75$

$\Rightarrow -1.25;-1.5;-1.75;2$