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a-b-c-N-Show-that-ab-lt-c-a-b-c-




Question Number 212741 by mathocean1 last updated on 22/Oct/24
a, b,c ∈ N^∗     Show that ab<c ⇒ a+b≤c
a,b,cNShowthatab<ca+bc
Answered by A5T last updated on 22/Oct/24
WLOG; let a≤b  ⇒2a=a+a≤a+b≤b+b=2b≤ab<c when a≥2  ⇒a+b<c  when a=1; ab=b<c⇒b+1≤c≡a+b≤c
WLOG;letab2a=a+aa+bb+b=2bab<cwhena2a+b<cwhena=1;ab=b<cb+1ca+bc

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