Answer: C. 9x+6 yd
Step-by-step explanation:
Given: The length of Jin's house= [tex]3x+4\ yd[/tex]
The area of Jin's backyard=[tex]9x^2+15x+4\ yd^2[/tex]
By middle splitting method, The area of Jin's backyard=[tex]9x^2+12x+3x+4\ yd^2=(3x+1)(3x+4)\ yds[/tex]
To find the width of the backyard, divide the area by the length, we get
Width[tex]=\frac{(3x+1)(3x+4)}{(3x+4)}=3x+1[/tex]
According to the question, only three sides need to fence
[tex]Fencing=3x+1+3x+1+3x+4=9x+6\ yd[/tex]
