B) If a fish has traveled 4.2 miles in an hour. What is its oxygen consumption
b. 29i-20
c.-21i
d.29
Answer:
The value of the (2 – 5i)(p + q)i is 29i .
Option (a) is correct .
Step-by-step explanation:
As the expression given in the question.
= (2 - 5i) (p + q)i
Simplify the above
= (2 - 5i) (pi + qi)
= 2pi + 2qi - 5pi²- 5qi²
As i² = -1
Put in the above
= 2pi + 2qi + 5p +5q
= 2i × 2 + 2i × 5i + 5 × 2 + 5 × 5i
= 4i + 10i² + 10 + 25i
As i² = -1
= 4i - 10 + 10 + 25i
= 29i
Thus the value of the (2 – 5i)(p + q)i is 29i .
Option (a) is correct .
Equation 2: 3m = 4 + 4n
Step 1:
−3(m) = −3(8 + 2n) [Equation 1 is multiplied by −3.]
3m = 4 + 4n [Equation 2]
Step 2:
−3m = −24 − 6n [Equation 1 in Step 1 is simplified.]
3m = 4 + 4n [Equation 2]
Step 3:
−3m + 3m = −24 − 6n + 4n [Equations in Step 2 are added.]
Step 4:
0 = −24 − 2n
Step 5:
n = −12
In which step did the student first make an error?
Step 4
Step 3
Step 2
Step 1
The student first makes an error in the Step 3 where he addsequations in Step 2 to use the elimination method.
To create an equation in one variable using the elimination method, you can either add or subtract the equations. To eliminate a variable, add the equations when the coefficients of one variable are in opposition, and subtract the equations when the coefficients of one variable are in equality.
How to solve this problem?
Notice that the student uses the elimination method to solve the equations. In Step 1, he makes the coefficients of m equal in both equations. In Step 2, he simplifies the previous step. In Step 3, he wants to add both equations to create an equation in one variable. But He forgot to add 4 of Equation 2. It's a mistake.
Therefore the student first makes an error in the Step 3 where he addsequations in Step 2 to use the elimination method.
Know more about the elimination method here -
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