(1.3x³-1.8y²)×(1.8y²+1.3x³)

To solve this expression, we will use the distributive property of multiplication.

(1.3x³ - 1.8y²) × (1.8y² + 1.3x³) = 1.3x³ × 1.8y² + 1.3x³ × 1.3x³ - 1.8y² × 1.8y² - 1.8y² × 1.3x³

Now, let's simplify each term:

1.3x³ × 1.8y² = 2.34x³y²

1.3x³ × 1.3x³ = 1.69x^6

-1.8y² × 1.8y² = -3.24y^4

-1.8y² × 1.3x³ = -2.34x³y²

Putting it all together, we have:

(1.3x³ - 1.8y²) × (1.8y² + 1.3x³) = 2.34x³y² + 1.69x^6 - 3.24y^4 - 2.34x³y²

Simplifying further, we can combine like terms:

(2.34x³y² - 2.34x³y²) + 1.69x^6 - 3.24y^4 = 0 + 1.69x^6 - 3.24y^4

Therefore, the simplified expression is:

1.69x^6 - 3.24y^4