Question

Find the value of the expression (81x^2 + 16 y^2 – 72xy), when x = 2 and y = 3.​

Answer 1

Answer:

81x² + 16y² - 72xy = 36

Step-by-step explanation:

We have to find the value of the following expression:

81x² + 16y² - 72xy.

It is given that x = 2 and y = 3.

Putting the value of x and y in 81x² + 16y² - 72xy we get,

81x² + 16y² - 72xy = 81 × (2)² + 16 × (3)² - 72 × 2 × 3

= (81 × 4) + (16 × 9) - 432

= 324 + 144 - 432

= 468 - 432 = 36

∴ 81x² + 16y² - 72xy = 36