<span>x2 − 8x + 16
= (x - 4)(x - 4)
= (x - 4)^2</span>
Answer:
The correct answer is 15 cm.
Step-by-step explanation:
Let the width of the required poster be a cm.
We need to have a 6 cm margin at the top and a 4 cm margin at the bottom. Thus total margin combining top and bottom is 10 cm.
Similarly total margin combining both the sides is (4+4=) 8 cm.
So the required printing area of the poster is given by {( a-10 ) × ( a - 8) } 
This area is equal to 125
as per as the given problem.
∴ (a - 10) × (a - 8) = 125
⇒
- 18 a +80 -125 =0
⇒
- 18 a -45 = 0
⇒ (a-15) (a-3) = 0
By law of trichotomy the possible values of a are 15 and 3.
But a=3 is absurd as a
4.
Thus the required answer is 15 cm.
So to find the x vertex u have to apply the formula x= -b/2a so it will be
x= -(-4)/2(1)
x= 4/2
x= 2
and to find the y vertex u just substitute the x value into the original equation so it will be
y= (2)^2-4(2)+1
y= 4-8+1
y= -3
so the coordinates of the vertex are (2,-3)