Question

Find number of terms in the Arithmetic Progression: -1, -3, -5, -7,..., -151.​

Answer 1

Explanation:

Given,

a

=

10

,

last term

=

100

and

number of terms

=

1000

Sum of first

n

terms in an A.P. is

S

n

=

n

2

[First term

+

Last term]

=

1000

2

[

10

+

100

]

=

500

[

110

]

S

1000

=

55

,

000

Answer 2

$ANSWER$

$\LARGE\bold{ \red{ \boxed{\red{\underline{\blue{\underline{\green{\underline{\mathtt{\blue{ExpLaNAtiOn:↓}}}}}}}}}}}$

$\LARGE\bold{ \red{ \boxed{\blue{\underline{\mathtt{\red{Given:↓}}}}}}}$

${AP = -1, -3, -5, -7,... -151.}$

= t 1 = -1 , t 2 = -3 ,

= t 3 = -5 , t 4 = -7 ,

$\LARGE\bold{ \green{ \boxed{\blue{\underline{\mathtt{\green{given - that:↓}}}}}}}\\ \\ {a= -1 \: ,tn = -151}$

d= t 2 - t 1

= -3 -(-1)

= (-3) +1 = -2

$\sf \bf \huge {\boxed {\mathbb {Therefore}}}$

$d = -2$

$We \: know \: that$

$Tn = a+ (n -1) × d$

The half answered is in attachment .

$\LARGE{\red{\boxed{\purple{\underline{\blue{\underline{ \green{ \underline{\orange{\mathtt{Answer:↓}}}}}}}}}}}$

AP= 76

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