Question bank/JEE Main/Mathematics

JEE MainMathematicsModerateInequalities and absolute value

Identify the following statements for in order
Let X and Y be two sets.

S-
1:X∩(Y∪X)′=ϕ1:X \cap (Y \cup X)^{'} = \phi
S-
2  If X∪Y2\:\ If\ X \cup Y has m elements and X∩YX \cap Y has n elements
then symmetric difference
XΔYX\Delta Y has m - n elements.
S-
3: If ∣x−5∣+∣x−11∣=∣2x−16∣3:\ If\ |x - 5| + |x - 11| = |2x - 16|, then
x≤5 or x≥11x \leq 5\ or\ x \geq 11
S-
4:∣x−a∣+∣x−b∣=b−a4:|x - a| + |x - b| = b - a has infinitely many solutions, for
a<b.

Show answer and solution
[IMAGE] S-2: n(x∪y)=mn(x \cup y) = m
n(x∩y)=nn(x \cap y) = n
n(xΔy)=n(x∪y)−n(x∧y)n(x\Delta y) = n(x \cup y) - n(x \land y)
= m - n

S-3:
∣x−5∣+∣x−1∣∣=(2x−16)|x - 5| + |x - 1| \mid = (2x - 16)
Case 1: x < 5

- x + 5 - x +11 = - 2x + 16

(LHS = RHS)

Case 2:
5≤x<85 \leq x < 8
⇒x−5−x+11≠−2x+16\Rightarrow x - 5 - x + 11 \neq - 2x + 16
Case 3:
8≤x<118 \leq x < 11
x−5−x+11+2x−16x - 5 - x + 11 + 2x - 16
Case 4:
x≥11x \geq 11
n−5+x−11=2n−16n - 5 + x - 11 = 2n - 16
⇒  \Rightarrow \ \ (LHS = RHS)
S- 4:
∣n−a∣+∣x−b∣=b−a|n - a| + |x - b| = b - a
for a < b

Case 1: x < a

– x + a – x + b–\ x\ + \ a\ –\ x\ + \ b
=  – 2 x + a + b ≠b−a= \ \ –\ 2\ x\ + \ a\ + \ b\ \neq b - a
Case 2:
a<x<ba < x < b
x−a−x+b=b−ax - a - x + b = b - a
Case 3:
x>bx > b
x−a+x−bx - a + x - b
2x−a−b≠b−a2x - a - b \neq b - a

Source: Grass-G / M-05 Mathematics Paper 10 October.docx

Need a video for this idea?

Scan any doubt from your notes and get a whiteboard explanation.