Explanation

Using the change of base formula:

log_b^a / log_b^d = log_d^a

Explanation

Let's expand both expressions:

(a + b)² = a² + 2ab + b²

(a - b)² = a² - 2ab + b²

Now, add them:

(a + b)² + (a - b)² = a² + 2ab + b² + a² - 2ab + b²

= 2a² + 2b²

Explanation

Let's use the Pythagorean theorem:

Height of pole (perpendicular) = 12m

Length of string (hypotenuse) = 20m

Distance between foot of pole and end point of string (base) = √(hypotenuse² - perpendicular²)

= √(20² - 12²)

= √(400 - 144)

= √256

= 16m

Explanation

Given:

x̄ (mean) = 12

∑x (sum) = 132

The formula for mean is:

x̄ = ∑x / n

Rearrange to find n:

n = ∑x / x̄

= 132 / 12

= 11

Explanation

Cost price of 1 apple = 34 ÷ 8 = Rs. 4.25

Cost price of 12 apples = 4.25 × 12 = Rs. 51

Selling price of 12 apples = Rs. 57

Profit = 57 − 51 = Rs. 6 per dozen.

Explanation

Work = Persons × Days = 3 × 4 = 12 person-days

With 4 persons: 12 ÷ 4 = 3 days.

Explanation

Explanation

10% of 5400 = 540

5400 - 540 = 4860

Explanation

A pie chart represents data in a circular form, and the sum of all the angles in the chart always equals 360°.

Each slice of the pie chart corresponds to a portion of the total, and their angles add up to 360°.

Explanation

The correct phrase is "quick in mind," meaning intellectually sharp or intelligent.

"In" is the proper preposition to describe a quality within someone, like the mind.