Answer:
20m
Step-by-step explanation:
Area of garden = 400m²
Area = L² = 400m²
L = √400m²
L = 20m
 
        
                    
             
        
        
        
By solving the quadratic equation using completing the square method we got that Penelope should have added 4 to both sides instead of adding 1. 
<h3>What is quadratic equation ?</h3>
Any equation of the form  where x is variable and a, b, and c are any real numbers where a ≠ 0 is called quadratic equation .
 where x is variable and a, b, and c are any real numbers where a ≠ 0 is called quadratic equation .
Given work of Penelope is

Now we can see that Penelope determined the solutions of the quadratic function by completing the square. so he must have been done as following

By solving the quadratic equation using completing the square method we got that Penelope should have added 4 to both sides instead of adding 1. 
To learn more about quadratic equations visit : brainly.com/question/1214333
 
        
             
        
        
        
Answer:
=14
Step-by-step explanation:
In a rhombus, opposite angles are equal.
In the one provided in the question, 5x° is opposite the angle 70°
Let us equate the two.
5x=70
x=70/5
=14°
The value of x in the figure is 14°
 
        
             
        
        
        
-4 (x - 5) + 3 (a - 7)
First, expand your problem. / Your problem should look like: -4x + 20 + 3a - 21
Second, simplify. / Your problem should look like: -4x + 3a - 1
Answer: -4x + 3a - 1 (C)