Answer: x^2-3x+36
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Step-by-step explanation:
The larger rectangle has area of (x+1)(x+1) = x^2+2x+1 through the use of the FOIL rule or distribution
If you use distribution, then it might help to let y = x+1 so we'd have y(x+1) lead to xy+1y which becomes x(x+1)+1(x+1). From there it might be easier to see how to get x^2+2x+1 after everything distributes again and simplifies.
The smaller rectangle has area 5x-35 which is found by distributing 5(x-7)
To get the shaded area, we subtract the two rectangle areas found above
shaded area = (larger area) - (smaller area)
shaded area = (x^2+2x+1) - (5x - 35)
shaded area = x^2+2x+1 - 5x + 35
shaded area = x^2-3x+36