Answer:
The range is y ≥ -1
Step-by-step explanation:
∵ f(x) = (x - 4)(x - 2)
∴ f(x) = x² - 2x - 4x + 8
∴ f(x) = x² - 6x + 8 ⇒ quadratic function (ax² + bx + c) represented by
parabola graphically
∵ a = 1 , b = -6 , c = 8
∴ x-coordinate of its vertex = -b/2a = -(-6)/2×1 = 3
∴ f(3) = (3)² - 6(3) + 8 = -1
∵ a is positive ⇒ the curve has minimum point and it's open upward
∴ the minimum point is (3 , -1)
∴ The range is y ≥ -1 ⇒ because the minimum value is -1
Complete question :
A 12-foot by 15-foot patio is increased by placing a stone border around the patio. The width of the border is the same all around the patio.The perimeter of the patio after it is expanded is 74 feet. The equation which represents x, the width of the border is 2[(12+2x)+15+2x)]=74. What is the width of the border?
1) 2 1/2 feet
2) 3 feet
4) 5 feet
5) 8 1/2 feet
Answer:
2.5
Step-by-step explanation:
Solving for X in the perimeter equation :
2[(12+2x)+15+2x)]=74
Open the bracket
2[(12 + 2x + 15 + 2x)] = 74
2(27 + 4x) = 74
54 + 8x = 74
8x = 74 - 54
8x = 20
x = 20/8
x = 2.5
Hence, width fo border = 2.5
