Answer:
(x + 7)^2 = 64
Step-by-step explanation:
x^2 + 23x – 19 = 9x - 4
x^2 + 23x - 9x = -4 + 19
x^2 + 14x = 15 = 0
Completing the square:
(x + 14/2)^2 - (14/2)^2 = 15
(x + 7)^2 - 49 = 15
(x + 7)^2 = 64
You can multiply 8 times 9 to get 72 and then move the decimal over to the right to get the answer of 7.2
Solving for a variable means to rewrite the equation so that the desired variable is alone on one side. So, we have to "move" all the other variables/constants in order to make this happen. We are allowed to add/subtract the same quantity from both sides, or to multiply/divide both sides by any non-zero number.
Let's start with the first example: we are given
11. 
the variable 
is not alone on the right hand side because it is multiplied by 
. We can reverse this by dividing both sides by : the equation becomes
So, we have written the equation as 
, which means that now sits alone on one side of the equation, and thus we have solved the equation for !
Similarly, we do all the others:
12. 
Subtract 
from both sides to get
13. 
Subtract 
from both sides to get
Now divide both sides by 
to get
14. 
Multiply both sides by 2:
Divide both sides by 
:
The answer is 3:9 because it says that he sold 3 out of the 12 paintings and so it asks first of how many did he sell and he sold three and how many did he not sell and so it's nine left
