Answer:
Dimensions of printed area
x = 7.58 the length
y = 31.40 cm the height
Step-by-step explanation:
Printed region P(a) = 238 cm²
Let call x and y dimensions of printed area then:
A = 238 = x*y ⇒ y = 238/x
And the area of the advertisement is
A(a) = L * W where L = x + 6 and W = y + 5
A(x) = (x + 6 ) * ( y + 5 )
Area as a function of x y = 238/ x
A(x) = (x + 6 ) * ( 238/x + 5 )
A(x) = 238 + 5x + 1428/x + 30
A(x) = 268 + 5x + 1428/x
Taking derivatives on both sides of the equation
A´(x) = 5 - 1428/x²
A´(x) = 0 ⇒ 5x² = 1428 ⇒ x² = 57.12
x = 7.58 cm and y = 238/ 7.58 y = 31.40 cm
