Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the odd letter/letters from the given alternatives.

In the following question, four number pairs are given. The number on left side of (–) is related to the number on the right side of (–) with some Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.

If the roots of the equation a(b – c)x2 + b(c – a)x + c(a – b) = 0 are equal, then which of the following is true?

What is the value of √[(1 + sinA)/(1 -­ sinA)]?

What is the value of (1 + cotA)2 + (1 -­ cotA)2?

If 1/√(1 -­ sin2A) = x, then the value of x is

What is the value of xy if x - y = 3 and x2+y2=15?

Find the HCF & LCM of 16, 24.