ECON

marta [7]

The correct answer is: [A]: " 4x³ + x² − 11x + 15 " .

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Note:
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(6x³ − 4x + 5) − (2x³ − x² + 7x − 10) ;

= (6x³ − 4x + 5) − 1(2x³ − x² + 7x − 10) ;
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Examine the following portion of the expression:
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" − 1(2x³ − x² + 7x − 10) " ;

= (-1 * 2x³) − (-1 * x²) + (-1 * 7x) − (-1 * 10) ;

= (-2x³) − (-1x²) + (-7x) − (-10) ;

= (-2x³) + 1x² − 7x + 10 ;

= " − 2x³ + 1x² − 7x + 10 " ;

Now, bring down the other part:

6x³ − 4x + 5 − 2x³ + 1x² − 7x + 10 ;

Combine the "like terms" :

6x³ − 2x³ = + 4x³ ;

− 4x − 7x = − 11x ;

+ 5 + 10 = + 15 ;

and bring down the:

+ 1x² ( which equals: " x² ") ;
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And rewrite:
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→ " 4x³ + x² − 11x + 15 " ;

→ which is: Answer choice: [A]: " 4x³ + x² − 11x + 15 " .
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5 0

3 years ago

Tensile strength tests were performed on two different grades of aluminum spars used in manufacturing the wing of a commercial t

jekas [21]

Answer:

(12.1409, 14.0591

Step-by-step explanation:

Given that Tensile strength tests were performed on two different grades of aluminum spars used in manufacturing the wing of a commercial transport aircraft. From past experience with the spar manufacturing process and the testing procedure, the standard deviations of tensile strengths are assumed to be known.

Group Group One Group Two

Mean 87.600 74.500

SD 1.000 1.500

SEM 0.316 0.433

N 10 12

The mean of Group One minus Group Two equals 13.100

standard error of difference = 0.556

90% confidence interval of this difference:

$(13.1-1.725*0.556,13.1+1.725*0.556)\\=(12.1409, 14.0591)$