1
JEE Main 2021 (Online) 16th March Evening Shift
Numerical
+4
-1
Change Language
Let f : R $$ \to $$ R and g : R $$ \to $$ R be defined as

$$f(x) = \left\{ {\matrix{ {x + a,} & {x < 0} \cr {|x - 1|,} & {x \ge 0} \cr } } \right.$$ and

$$g(x) = \left\{ {\matrix{ {x + 1,} & {x < 0} \cr {{{(x - 1)}^2} + b,} & {x \ge 0} \cr } } \right.$$,

where a, b are non-negative real numbers. If (gof) (x) is continuous for all x $$\in$$ R, then a + b is equal to ____________.
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2
JEE Main 2021 (Online) 16th March Evening Shift
Numerical
+4
-1
Change Language
Consider the statistics of two sets of observations as follows :

Size Mean Variance
Observation I 10 2 2
Observation II n 3 1


If the variance of the combined set of these two observations is $${{17} \over 9}$$, then the value of n is equal to ___________.
Your input ____
3
JEE Main 2021 (Online) 16th March Evening Shift
Numerical
+4
-1
Out of Syllabus
Change Language
Let n be a positive integer. Let

$$A = \sum\limits_{k = 0}^n {{{( - 1)}^k}{}^n{C_k}\left[ {{{\left( {{1 \over 2}} \right)}^k} + {{\left( {{3 \over 4}} \right)}^k} + {{\left( {{7 \over 8}} \right)}^k} + {{\left( {{{15} \over {16}}} \right)}^k} + {{\left( {{{31} \over {32}}} \right)}^k}} \right]} $$. If

$$63A = 1 - {1 \over {{2^{30}}}}$$, then n is equal to _____________.
Your input ____
4
JEE Main 2021 (Online) 16th March Evening Shift
Numerical
+4
-1
Change Language
Let $$A = \left[ {\matrix{ {{a_1}} \cr {{a_2}} \cr } } \right]$$ and $$B = \left[ {\matrix{ {{b_1}} \cr {{b_2}} \cr } } \right]$$ be two 2 $$\times$$ 1 matrices with real entries such that A = XB, where

$$X = {1 \over {\sqrt 3 }}\left[ {\matrix{ 1 & { - 1} \cr 1 & k \cr } } \right]$$, and k$$\in$$R.

If $$a_1^2$$ + $$a_2^2$$ = $${2 \over 3}$$(b$$_1^2$$ + b$$_2^2$$) and (k2 + 1) b$$_2^2$$ $$\ne$$ $$-$$2b1b2, then the value of k is __________.
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