The area of a rectangular painting is given by the trinomial x^2+4x-21
To find the area of a rectangular painting, we need to calculate the product of its length and width. The trinomial x^2+4x-21 can be factored as (x+7)(x-3). Therefore, the length of the painting is (x+7), and the width is (x-3).
The area is given by multiplying the length and width:
Area = (x+7)(x-3)
We can simplify this expression by using the distributive property:
Area = x(x-3) + 7(x-3)
Now, we can continue to simplify the expression:
Area = x^2 - 3x + 7x - 21
Combining like terms, we have:
Area = x^2 + 4x - 21
So, the area of the rectangular painting is x^2 + 4x - 21.