Element A:
If tan−1(x2+x+a4)
x2+x+a4>0
⇒(x+12)2+(a−14)>0,∀xϵR
⇒a−1>0
⇒a>1
Therefore, smallest [a]=1
Element B:
x2−3x+2x2−7x+10<0
⇒(x−1)(x−2)(x−2)(x−5)<0,x≠2
→xϵ(1,5)−2
⇒x=3
Element C:
[→a×→b→a→b]=[→a→b→a×→b]=(→a×→b)⋅(→a×→b)
=|→a×→b|2=4
Element D:
f(x)=|x−0.5|+|x2−1|+|x−2|
For x∈(−2,2) we have,
f(x)=−x+0.5+x2−1−x+2 for −2<x<−1
f(x)=−x+0.5−x2+1−x+2 for −1<x<0.5
f(x)=x−0.5−x2+1−x+2 for 0.5<x<1
f(x)=x−0.5+x2−1−x+2 for 1<x<2
By calculating the derivative we find that f′(x) is discontinuous at x=−1,0.5,1,
Hence, 3 points.