Chapter 7 - Polynomial Equations and Factoring - 7.2 - Multiplying Polynomials - Exercises - Page 369: 31

$\text{Area}=2x^{2}+x-45$

$\text{Area of the shaded region}=\text{Area of the rectangle}=\text{length}\times\text{breadth}$ $\implies \text{Area}=(x+5)(2x-9)$ Using FOIL (First Outer Inner Last) method, we have $\text{Area}=2x^{2}-9x+10x-45$ Combining like terms, we get $\text{Area}=2x^{2}+x-45$