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frozen [14]
4 years ago
13

If f(x)=3x^2-7 , find f(4). Show all work

Mathematics
2 answers:
katrin2010 [14]4 years ago
4 0
Plug in all x's for 4.  4^2 = 16 --> 16x3=48 --> 48-7 = 41 
41 is the final answer
vagabundo [1.1K]4 years ago
4 0
<span>f(x)=3x</span>²<span>-7

Simply insert value of x, 4 into the equation then simplify
f(4)=3(4)</span>²-7
     =3(16)-7
     = 48 -7
     = 41
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Simplify:<br> 2(xy - 7) = [?]<br> x = -1 and y = 3
fiasKO [112]

Answer:2(xy-7)= -20

Step-by-step explanation:

Plug in -1 for x and 3 for 3, as the question says that x and y represent those values.

2(xy-7) = ?

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5 0
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4 years ago
Two sections of a class took the same quiz. Section A had 15 students who had a mean score of 80, and Section B had 20 students
Nezavi [6.7K]

Answer: A. 85.7

Step-by-step explanation:

Given : Two sections of a class took the same quiz.

Section A had 15 students who had a mean score of 80, and Section B had 20 students who had a mean score of 90.

We know that  , \text{Mean}=\dfrac{\text{Sum of observations}}{\text{No. of observations}}

Then , for section A :

\text{Mean score }=\dfrac{\text{Sum of scores in sec A}}{\text{No. of students}}

\Rightarrow\ 80=\dfrac{\text{Sum of scores in sec A}}{15}\\\\\Rightarrow\ \text{Sum of scores in sec A}=80\times15=1200

Similarly in Section B, \text{Sum of scores in sec B}=90\times20=1800

Total scores = Sum of scores in sec A+Sum of scores in sec B

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Total students = Students in sec A +Students in sec B

=15+20=35

Now , the mean score for all of the students on the quiz =\dfrac{\text{Total score}}{\text{Total students}}

=\dfrac{3000}{35}=85.7142857143\approx85.7

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Thus , the correct answer is option A. 85.7.

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