Question

A library building is in the shape of a rectangle. Its floor has a length of (3x + 5) meters and a width of (5x − 1) meters. The expression below represents the area of the floor of the building in square meters:
(3x + 5)(5x − 1)

Which of the following simplified expressions represents the area of the floor of the library building in square meters?

28x − 5
15x2 − 5
15x2 + 28x − 5
15x2 + 22x − 5

Answer 1

We can use the Front Outside Inside Last (FOIL) method to expand the double bracket

$(3x+5)(5x-1)$

Front ⇒$(3x)(5x)=15 x^{2}$
Outside ⇒$(3x)(-1)=-3x$
Inside ⇒$(5)(5x)=25x$
Last ⇒$(5)(-1)=-5$

Put the four terms together we have
$15 x^{2} -3x+25x-5$, then collect like terms
$15 x^{2} +22x-5$

Answer 2

Answer:

15 x^{2} +22x-5

Is the answer:)