Words Given:
Logical Order:
3 → 1 → 2 → 4 → 5
Explanation:
Step 1: One-one (injective) function means no two elements map to the same output.
We choose 3 different elements from 5 and assign them to 3 inputs in order.
So, total one-one functions = $P(5,3) = 5 \times 4 \times 3 = 60$
✅ Final Answer: $\boxed{60}$
Vectors:
Step 1: Volume = $|\vec{a} \cdot (\vec{b} \times \vec{c})|$
First compute $\vec{b} \times \vec{c}$:
$ \vec{b} \times \vec{c} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 1 & -1 & 1 \\ 1 & 2 & -1 \end{vmatrix} = \hat{i}((-1)(-1) - (1)(2)) - \hat{j}((1)(-1) - (1)(1)) + \hat{k}((1)(2) - (-1)(1)) \\ = \hat{i}(1 - 2) - \hat{j}(-1 - 1) + \hat{k}(2 + 1) = -\hat{i} + 2\hat{j} + 3\hat{k} $
Step 2: Compute dot product with $\vec{a}$:
$\vec{a} \cdot (\vec{b} \times \vec{c}) = (m)(-1) + (1)(2) + (1)(3) = -m + 2 + 3 = -m + 5$
Step 3: Volume = $| -m + 5 | = 4$
So, $|-m + 5| = 4 \Rightarrow -m + 5 = \pm 4$
✅ Final Answer: $\boxed{m = 1 \text{ or } 9}$
Given:
Calculations:
✅ Difference: 120 km – 90 km = 30 km
Condition: Vectors are coplanar ⟹ Scalar triple product = 0
$\vec{a} \cdot (\vec{b} \times \vec{c}) = 0$
Step 1: Use determinant:
$ \vec{a} \cdot (\vec{b} \times \vec{c}) = \begin{vmatrix} \lambda^2 & 1 & 1 \\ 1 & \lambda^2 & 1 \\ 1 & 1 & \lambda^2 \end{vmatrix} $
Step 2: Expand the determinant:
$ = \lambda^2(\lambda^2 \cdot \lambda^2 - 1 \cdot 1) - 1(1 \cdot \lambda^2 - 1 \cdot 1) + 1(1 \cdot 1 - \lambda^2 \cdot 1) \\ = \lambda^2(\lambda^4 - 1) - (\lambda^2 - 1) + (1 - \lambda^2) $
Simplify:
$= \lambda^6 - \lambda^2 - \lambda^2 + 1 + 1 - \lambda^2 = \lambda^6 - 3\lambda^2 + 2$
Step 3: Set scalar triple product to 0:
$\lambda^6 - 3\lambda^2 + 2 = 0$
Step 4: Let $x = \lambda^2$, then:
$x^3 - 3x + 2 = 0$
Factor:
$x^3 - 3x + 2 = (x - 1)^2(x + 2)$
So, $\lambda^2 = 1$ (double root), or $\lambda^2 = -2$ (discard as it's not real)
Thus, real values of $\lambda$ are: $\lambda = \pm1$
✅ Final Answer: $\boxed{2}$ distinct real values
Given:
Step-by-Step:
✅ Final Answer: The trader marks the goods 38.89% above the cost price.
We are asked to count permutations of bottles such that exactly 5 bottles go into their own numbered boxes.
Step 1: Choose 5 positions to be fixed points (i.e., bottle number matches box number).
Number of ways = $\binom{9}{5}$
Step 2: Remaining 4 positions must be a derangement (no bottle goes into its matching box).
Let $D_4$ be the number of derangements of 4 items.
$D_4 = 9$
Step 3: Total ways = $\binom{9}{5} \times D_4 = 126 \times 9 = 1134$
✅ Final Answer: $\boxed{1134}$
Online Test Series, Information About Examination,
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Online Test Series, Information About Examination,
Syllabus, Notification
and More.
Commented Mar 17, 2025
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