Answer:
20÷[18-{20-3(4)}]
120÷[18-[20-12]]
120÷[18-8]]
120÷10
12
Step-by-step explanation:
If you expand out the brackets you get this,
(4+5i)(a+2i) = 4a + (5a)i + 8i - 10
The -10 comes from 5i * 2i.
Squaring i becomes -1.
Let's group the real stuff together,
and imaginary separately,
(4a - 10) + (5a + 8)i
For this to be purely imaginary,
the real part needs to be zero.
Therefore 4a - 10 = 0
Solve for a.
Answer: The answer is (C).
Step-by-step explanation: The given statement is - "Two matrices are row equivalent if they have the same number of rows". We are to explain whether the statement is true or false.
What are row equivalent matrices? The answer to this question is -
Two matrices are said to be row equivalent if one of the matrices can be obtained from the other by applying a number of elementary row operations. Or, we can say two matrices of same order are row equivalent if they have same row space.
Thus, the correct option is (C).
Riya’s BMI is 20 which means she is a normal weight. Her brother’s BMI is 18.7, which is low but is still a normal weight. So yes, their heights are proportioned to their weights.