DS 7

Question

Explainations please...

hallelujah1234 · Answer

xyz = 1 (2)
or x = y = 1 (2)

x(y^2+z^3) = 0 (2), or even number

B is the answer.

Makky07 · Answer

B is sufficient.

If xyz is odd, then x, y and z are odd and x(y^2 + z^3) is even.

Statement 1 is insufficent; we don't know anything about y and z.

Abacus · Answer

Ndidi,

Coud you please elaborate your sentence,
"If xyz is odd, then x, y and z are odd and x(y^2 + z^3) is even. "


Thanks.

Makky07 · Answer

Hi Abacus,

If xyz is odd, then x, y and z are odd and x(y^2 + z^3) is even. 


If xyz is odd, it means that x is odd, y is odd and z is odd. If any one of the three is even, then xyz would be even. Remember that 2 is a factor of every even number so x, y or z cannot be even.

If x, y and z are odd, then:

odd(odd^2 + odd^3) = even

odd^2 + odd^3 is even since the sum of 2 odd numbers is even.

odd * even is also even.

Abacus · Answer

Hi ndidi,

Thank you for your explanation.

DS 7

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