Answer: A, B, C, and E
Step-by-step explanation:
If both sides are real numbers, then the product will be a real number.
If in at least one of the sides we have a complex number, then the product will be real if:
The other number is zero.
The other number is the conjugate of the first.
This is when:
Suppose we have a number:
z = a + b*i
The conjugate will be:
w = a - b*i
And the product between them is:
(a + b*i)*(a - b*i) = a^2 + a*b*i - a*b*i + b^2 = a^2 + b^2
Then the options that will have a real answer are:
A. (4+5i)(4-5i) = 4^2 + 5^2 = 16 + 25 = 41
B. (4 + 91)*(41 - 9) = 3040
C. (3 + 2*i)*(3 -2*i) = 3^2 + 2^2 = 9 + 4 = 13
E. (312 + 7i)*(312 - 7i) = 312^2 + 7^2 = 97,393
Answer:
Weight of cereal in box in pound is 1.32277 pound
Given that;
Weight of cereal in box = 600 grams
Find:
Weight of cereal in box in pound
Computation:
1 gram = 0.00220462 pound
So,
600 gram = 600 × 0.00220462 pound
600 gram = 1.32277
Weight of cereal in box in pound = 1.32277 pound
Step-by-step explanation:
<h2>HOPE IT HELPS YOU</h2>
3< -5x+2x
3< -3x
-3x>3
3x> -3
X> -1
Answer:
5
Step-by-step explanation:
3*1*5/3=5
<h3>The first time when the ball will reach a height of 20 feet is 0.42 seconds</h3>
<em><u>Solution:</u></em>
Given that,
<em><u>The height of a ball thrown into the air after t seconds have elapsed is:</u></em>
<em><u>What is the first time, t, when the ball will reach a height of 20 feet?</u></em>
Substitute h = 20
<em><u>Solve by quadractic formula</u></em>
Rounding off we get,
t = 2.08 , t = 0.42
Thus the first time when the ball will reach a height of 20 feet is 0.42 seconds
