Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the odd word from the given alternatives.

select the odd word/letters/number/number pair from the given alternatives.

What is the value of cos2A/(1 + sinA)?

What is the value of 2 - 2z + z22 + 2z - z2, when z+2z = 2 ?

If the selling price is Rs 1680 after getting a discount of 16%, what was the marked price?

If a4 + 1 = [a2 /b2 ] (4b2 – b4 – 1), then what is the value of a4 + b4?

If a + b = 1, then a4 + b4 - a3 - b3 - 2a2b2 + ab is equal to

If sec θ (cos θ + sin θ) = √2, then what is the value of (2 sin θ)/(cos θ – sin θ)?