Question

for an AP t2 =-1and T5=5 then t1=​

Answer 1

Answer:

-3

Step-by-step explanation:

t2 = a + d = -1

t5 = a + 4d = 5

So, a + 4d - a - d = 3d = 5-(-1) = 5+1 = 6

=> d = 2

a + 2 = -1

=> a = -3

So, t1 = a = -3

Answer 2

Answer:

Given ;

→t2 = -1 → t5 = 5

We know that,

$\color{yellow} \boxed {tn \: = a + (n - 1)d}$

$\implies \: t2 = a + d \: = - 1 \:$

............................................. --------> eq 1

Similarly ,

$\implies \: t5 = a + 4d = 5$

..............................................--------> eq 2

eq 2 - eq 1,

$\leadsto \large3d = 6$

$\leadsto \large \boxed{d = 2}$

Substituting in eq 1,

=> a + 2 = -1

=> a = - 3

$\therefore \huge \blue{t1 = - 3}$

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