CTET Solved Paper - CTET Feburary 2016 Paper2
142. One of the factors of x4 + 4 is
- Option : C
- Explanation : x4 + 4 = (x2)2 + (2)2
= (x2 + 2)2 - 2.(x2).(2) [As a2 + b2 = (a+b)2 - 2ab]
= (x2 + 2)2 - 4x2
= (x2 + 2)2 - (2x)2
= (x2 + 2 + 2x)(x2 + 2 - 2x) [As a2 - b2 = (a+b)(a-b)]
∴ (x2 - 2x + 2) is a factor of x4 + 4.
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- Option : D
- Explanation : Given, the mean of the 5 observations x, x + 2, x + 4, x + 6, x + 8 is 11.
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- Option : B
- Explanation : Given, a bag contains 5 red marbles, 4 green marbles and 3 blue marbles.
Total number of marbles = 12.
Total number of non-green marbles =8
Here, total number of cases =12 and number of favourable cases = 8
.'. Probability of getting a non-green marble =
Number of favourable cases/Total number of cases.
= 8/12. = 2/3.
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- Option : B
- Explanation : Given, AB x BA = BCB.
Here, we cannot take AB as 11 because from question A ≠ B ≠ C.
If we take A = 1 and B = 2, then 12x21 = 252.
From, here we can say that A = 1, B = 2 and C = 5
.'. A + B + C = 1 + 2 + 5 = 8.
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