Question

A rectangle has sides measuring (2x + 7) units and (5x + 9) units.

Part A: What is the expression that represents the area of the rectangle? Show your work to receive full credit. (4 points)

Part B: What are the degree and classification of the expression obtained in Part A? (3 points)

Part C: How does Part A demonstrate the closure property for polynomials? (3 points)

Answer 1

@welshfella

Answer 2

Part A:
(2x+7)(5x+9)
=(2x+7)(5x+9)
=(2x)(5x)+(2x)(9)+(7)(5x)+(7)(9)
=10x2+18x+35x+63
=10x2+53x+63

Answer 3

thats what i have so far

Answer 4

area is length * width

\[(2x+7)(5x+9)\]

so we would expand this out. yep you're on the right track.

Answer 5

yes

Answer 6

thanks

Answer 7

can you guys explain the next part

Answer 8

im kinda confused

Answer 9

the degree is the value of the highest power That is 2.

Answer 10

oh yah i forgot

Answer 11

thanks

Answer 12

as for the classification i think in US its called a trinomial . In UK we would tend to call it a quadratic.

Answer 13

yup

Answer 14

i used to live in uk

Answer 15

Part C - same answer as previous Q.

Answer 16

OH OK! Where are you now?

Answer 17

US

Answer 18

used to live in england

Answer 19

anyway i still dont get Part C

Answer 20

2x + 7 and 5x + 9 are both polynomials ( in fact they are binomials) - multiplying them gives another polynomial. This demonstrates that polynomials are closed under multiplication.

Answer 21

thanks! again

Answer 22

yw