Answer:
a = 9
Step-by-step explanation:
First we need to add (x^2+3x) to (3x^2+ax),
(x^2+3x)+(3x^2+ax)
Expand
= x^2+3x+3x^2+ax
Collect the like terms
= x^2+3x^2+3x+ax
= 4x^2 + 3x + ax
= 4x^2+(3+a)x
Equate the solution to 4x^2+12x
4x^2+(3+a)x = 4x^2+12x
Comparing the like terms on both sides
(3+a)x =12x
3 + a = 12
a = 12 - 3
a = 9
Hence the value of a is 9
Answer:
Third option is correct!
Step-by-step explanation:
x+19<28
or, x<9
so
x = {3,4,5,6}
Answer:

Step-by-step explanation:
The missing details in the question are:


Required
The perimeter
This is calculated as:

So, we have:

Open bracket

Rewrite as:

Answer:
Step-by-step explanation:
I think its substitution