Question

Find $a,b$ such that $7.2,a,b,3$ are in AP.

Answer 1

Given $7.2,a,b,3$ are in $A.P$

$⟹7.2,a,b$ are in $A.P$

$⟹2a=7.2+b⟹b=2a-7.2$

and also $a,b,3$ are in $A.P$

$⟹2b=a+3⟹2(2a-7.2)=a+3$

$⟹4a-14.4=a+3$

$⟹3a=17.4⟹a=5.8$

$b=2\left(5.8\right)-7.2=11.6-7.2=4.4$