A rectangular lawn has a width of 3x m The area is 15x^2 + 45x m^2 you want to put the fence around the lawn. a) What is the expression to represent the perim

Question

 

 I am just new at these questions and having a hard time starting. 

I understand the P=2w+2l, however how do i solve when given area 

Answer 1

Hi Melis;

Area=(15x² + 45x)m²

Area=(length)(width)

Width= 3x m

We need to factor the area-equation, which must involve factoring out 3x m...

(3x m)[(5x+15)m]

(3x)(5x)=15x²

(3x)(15)=45x

(m)(m)=m²

The length is (5x+15)m

P=2w+2l

P=[2(3x m)]+[2(5x+15)(m)]

P=(6x+10x+30)m

P=(16x+30)m

 

 

Answer 2

15X^2 + 45x  = 5X^2 + 15     ? expression of lenghth

       3X

 

 P _{perimeter = 2 L + 2 W = 2( 5X^2 + 15) + 2( 3x)} =

                                       

                                    =  10 X^2 + 6X + 30