alleryIf $\vec a = 4\hat i + 3\hat k$ and $\vec b = -2\hat i + \hat j + 5\hat k$, then $2\vec a + 5\vec b$ equals:
A$-2\hat i + 5\hat j + 31\hat k$
B$18\hat i + 5\hat j + 31\hat k$
C$2\hat i + 5\hat j - 31\hat k$
D$-2\hat i + \hat j + 8\hat k$
Answer & Solution
Correct answer: A. $-2\hat i + 5\hat j + 31\hat k$
$2\vec a = 8\hat i + 6\hat k$
$5\vec b = -10\hat i + 5\hat j + 25\hat k$.
**Sum:** $-2\hat i + 5\hat j + 31\hat k$.
Keep practising Vector Algebra
Browse all Vector Algebra questions for GRE, or explore more Mathematics topics.
Related questions
Find a unit vector in the direction of $\vec a = \hat i - 2\hat j$:Vector $\vec{AB} = 2\hat i - 4\hat j + 7\hat k$ has initial point $A(1, 5, 0)$. The terminIf vectors $2\hat i - q\hat j + 3\hat k$ and $4\hat i - 5\hat j + 6\hat k$ are collinear, The position vector of the centroid of the **tetrahedron** with vertices $A(\vec a), B(\veVectors $\vec a = \hat i - 2\hat j + 3\hat k$ and $\vec b = 3\hat i - 6\hat j + 9\hat k$ aThe point dividing the line segment joining $A(2, -6, 8)$ and $B(-1, 3, -4)$ internally inThe distance from the point $P(2, 3, 4)$ to the **x-axis** is:Vector $\vec a$ is directed due north with $|\vec a| = 24$ and vector $\vec b$ is directed