Q. What is the average value of 3x on the interval −5≤x≤9 ?Choose 1 answer:(A) 563⋅(493−453)(B) 563⋅(394−354)(C) 21⋅(39−3−5)(D) 21⋅(39+3−5)
Set up integral: To find the average value of a function f(x) on the interval [a,b], we use the formula:Average value = (b−a)1⋅∫abf(x)dxHere, f(x)=3x=x31, a=−5, and b=9.
Calculate interval length: First, we need to set up the integral to find the average value:Average value = (1/(9−(−5)))×∫−59x(1/3)dx
Apply power rule: Calculate the denominator of the fraction, which is the length of the interval: 9−(−5)=9+5=14
Evaluate antiderivative: Now, the average value formula becomes:Average value = (1/14)×∫−59x(1/3)dx
Substitute values: To integrate x31, we use the power rule for integration, which states that ∫xndx=n+1xn+1+C, where C is the constant of integration. Here, n=31.
Find average value: Applying the power rule, we get:∫x31dx=31+1x31+1+C= 34x34+C= 43⋅x34+C
Match with options: Now we need to evaluate this antiderivative from −5 to 9:(43)⋅[x(34)] from −5 to 9= (43)⋅[9(34)−(−5)(34)]
Match with options: Now we need to evaluate this antiderivative from −5 to 9:(43)⋅[x(34)] from −5 to 9=(43)⋅[9(34)−(−5)(34)]Since we are dealing with real numbers, the cube root of a negative number is negative, and raising it to the fourth power will give us a positive result. So, (−5)(34) is the same as (5(31))4, which is 5(34).
Match with options: Now we need to evaluate this antiderivative from −5 to 9: (43)⋅[x(34)] from −5 to 9 = (43)⋅[9(34)−(−5)(34)]Since we are dealing with real numbers, the cube root of a negative number is negative, and raising it to the fourth power will give us a positive result. So, (−5)(34) is the same as (5(31))4, which is 5(34).Now we substitute the values into the expression: (43)⋅[9(34)−5(34)]
Match with options: Now we need to evaluate this antiderivative from −5 to 9: (43)⋅[x(34)] from −5 to 9 = (43)⋅[9(34)−(−5)(34)]Since we are dealing with real numbers, the cube root of a negative number is negative, and raising it to the fourth power will give us a positive result. So, (−5)(34) is the same as (5(31))4, which is 5(34).Now we substitute the values into the expression: (43)⋅[9(34)−5(34)]Finally, we multiply this by the reciprocal of the interval length to find the average value: Average value = 90 = 91
Match with options: Now we need to evaluate this antiderivative from −5 to 9: (3/4)⋅[x(4/3)] from −5 to 9 = (3/4)⋅[9(4/3)−(−5)(4/3)]Since we are dealing with real numbers, the cube root of a negative number is negative, and raising it to the fourth power will give us a positive result. So, (−5)(4/3) is the same as (5(1/3))4, which is 5(4/3).Now we substitute the values into the expression: (3/4)⋅[9(4/3)−5(4/3)]Finally, we multiply this by the reciprocal of the interval length to find the average value: Average value = 90 = 91We can now match our result with the given options. The correct answer is: (B) 92
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