Answer:
Part A. C=9
Part B. (w+3)² =139
Part C. w = 8.8 inch
Explanation:
Given from the question length of the the picture = (2w+12) inches
Width of the picture = w inches
Area of the picture = 260 inch²
Part A. Area of the picture with the given dimensions= w×(2w+12)
Or w(2w+12) = 260
2w²+12w = 260
2(w²+6w) = 2×(130)
w²+6w = 130
Or w²+6w +9 = 130+9 ⇒ which is in the form of w²+6w+c = 130+c
Therefore for c = 9 we will get a perfect square trinomial.
Part B. As we have seen the equation in part A.
As required equation will be (w+3)²=139
Part C. Since (w+3)² = 139
Then by taking under root on both the sides of the equation
(w+3) =√139 = 11.8
(w+3)-3=11.8-3
w = 8.8 inch