Explanation

For matrices A × B ≠ B × A in general, so matrix multiplication is not commutative.

However, matrix addition is commutative and associative, and matrix multiplication is associative, but not commutative.

Explanation

A preposition is typically followed by a noun or pronoun to complete its meaning.

Example: "She sat on the chair." — "on" (preposition) is followed by "the chair" (noun).

Explanation

To find the slope of the tangent to the curve y³x + y²x² = 6 at (2, 1), we'll use implicit differentiation:

Given: y³x + y²x² = 6

Differentiating both sides with respect to x:

y³ + x_3y²(dy/dx) + y²_2x + x²*2y(dy/dx) = 0

Rearranging terms to isolate dy/dx:

(3xy² + 2x²y)(dy/dx) = -y³ - 2xy²

dy/dx = (-y³ - 2xy²) / (3xy² + 2x²y)

Now, evaluating dy/dx at (2, 1):

dy/dx = (-(1)³ - 2_2_(1)²) / (3_2_(1)² + 2*(2)²*1)

= (-1 - 4) / (6 + 8)

= -5 / 14

Explanation

The derivative of 2^(-x) is -2^(-x) * ln(2), which can be written as -2⁻ˣ·log2 (considering log as ln or log base e implicitly in the derivative formula).

Explanation

The set {x: x ∈ N, x ≤ 10} has 10 elements (1, 2, 3, 4, 5, 6, 7, 8, 9, 10).

The cardinality of the power set of a set with n elements is 2^n.

So, the cardinality of the power set is 2^10 = 1024.

Explanation

Total ways to draw 3 balls = C(15, 3) = 455

Ways to draw 3 red balls = C(5, 3) = 10

Probability = 10/455 = 2/91

Explanation

Skew lines are lines that are not parallel and do not intersect, and they exist in three-dimensional space.

They lie in different planes, unlike parallel or intersecting lines.

Explanation

The given partial differential equation:

∂²U/∂x² + ∂²U/∂y² = f(x,y)

is known as the Poisson equation.

If f(x,y) = 0, it would reduce to the Laplace equation.

Explanation

Step 1: Evaluate the integral

∫(x² - x - 1) dx = (x³ / 3) - (x² / 2) - x

Step 2: Apply the limits of integration

[(1³ / 3) - (1² / 2) - 1] - [((-1)³ / 3) - ((-1)² / 2) - (-1)]

= [(1/3) - (1/2) - 1] - [(-1/3) - (1/2) + 1]

Step 3: Simplify the expression

= (1/3) - (1/2) - 1 + (1/3) + (1/2) - 1

= (2/3) - 2

= (2/3) - (6/3)

= -4/3

Explanation

Given y = acos(x) + bsin(x) + 4

First derivative: dy/dx = -asin(x) + bcos(x)

Second derivative: d²y/dx² = -acos(x) - bsin(x)

Notice that d²y/dx² = -(acos(x) + bsin(x))

Given y = acos(x) + bsin(x) + 4, we rearrange to find acos(x) + bsin(x) = y - 4

Substituting into the second derivative equation gives:

d²y/dx² = -(y - 4)

d²y/dx² = -y + 4

d²y/dx² + y = 4

The answer is d²y/dx² + y = 4.