(x - 4)(x + 3) = x^2 + 3x - 4x - 12 = x^2 - x - 12
Since 1A claims that the diagram is of a square, you can easily find the perimeter by multiplying just one side by 4, because the definition of a square says that all of its four sides are equal in length.
Take the left side, x and 4, and add them together, because both of these lengths add up to form the side of the square. You have found one side of the square, x + 4. Now multiply this side by 4 for the perimeter.
Perimeter is the length all around the figure, and since a square has 4 sides you would multiply one side by 4 to find the perimeter.
4(x + 4) is your expression for the perimeter of the square. You could probably solve 1B and 1C by substituting in 3 and 5 for x in the equation I've given you :)
Given:
y varies directly with x,
It is given that y = 7 when x = -9.
To find:
The value of y when x = 27 for the direct variation.
Solution:
It is given that y varies directly with x, so
...(i)
Where, k is the constant of proportionality.
It is given that y = 7 when x = -9. Putting these values in (i), we get
Putting 
in (i), we get
Putting 
, we get
Therefore, the required value is .
