9x²-0x-4
=9x²-4
=(3x-2)(3x+2) is the factor form of 9x²-0x-4
Solve for x:
3x-2=0
Add 2 to each side
3x-2+2=0+2
3x=2
Divided 3 to each side
3x/3=2/3
x=2/3
Or
3x+2=0
Subtract 2 to each side
3x+2-2=0-2
3x=-2
Divided 3 to each side
3x/3=-2/3
x=-2/3. Hope it help!
        
             
        
        
        
The assumptions of a regression model can be evaluated by plotting and analyzing the error terms.
Important assumptions in regression model analysis are 
- There should be a linear and additive relationship between dependent (response) variable and independent (predictor) variable(s). 
- There should be no correlation between the residual (error) terms. Absence of this phenomenon is known as auto correlation.
- The independent variables should not be correlated. Absence of this phenomenon is known as multi col-linearity.
- The error terms must have constant variance. This phenomenon is known as homoskedasticity. The presence of non-constant variance is referred to heteroskedasticity.
-  The error terms must be normally distributed.
Hence we can conclude that the assumptions of a regression model can be evaluated by plotting and analyzing the error terms.
Learn more about regression model here
brainly.com/question/15408346
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Answer:
Speed of plane in still air: 490  mile/hour
speed of wind: 70  mile/hour
Step-by-step explanation:
still speed = x        wind speed = w
with wind: speed = still + wind
(x+w) * 3 = 1680     ...a
against wind: speed = still - wind
(x-w) * 4 = 1680    ...b
b-a ... 4x-4w-3x-3w = 0
x-7w = 0
x = 7w
substitution: (7w+w)*3 = 1680      8w = 560       wind speed (w) = 70
still speed (x) = 7w = 490 mile/hour
 
        
             
        
        
        
Answer:
yeet
Step-by-step explanayeettion:
10
 
        
             
        
        
        
Answer: 
30
Step-by-step explanation:
x = 7
( x - 4 )^2 + 3x
= ( 7 - 4 )^2 + 3 ( 7 )
= 3^2 + 21
= 9 + 21
= 30