11) 7 + -10+(4(5+-3)) = 7+-10+8=5
12) (12 +-10)+3x+-1(2x+4x), 12+-10x+3x+-2x+-4x = 12+-13x
Answer: The value of x =2 units.
Explanation:
Since we have given that
AD= CD
BE= EA
So, we get that D and E are the mid-points of AC and AB respectively.
So, by Mid- point theorem , which states that the line joining the two midpoints is parallel to third side and it is half in length of third side i.e.

So, we put the value of DE and BC ,

Hence, the value of x =2 units.
3 if by the x axis 4 if by the y axis
Answer:
19
Step-by-step explanation:
Given 2 sides of a triangle then the third side x is
difference of 2 sides < x < sum of 2 sides , that is
18 - 2 < x < 18 + 2
16 < x < 20
Then the largest possible length of the third side is 19