4. The three elements of a sinusoidal signal are () A. amplitude B. frequency C. effective value D. phase 4. The three elements of sine signal are () A. Range B. Frequency C. Effective value D. Phase

4. The three elements of a sinusoidal signal are () A. amplitude B. frequency C. effective value D. phase 4. The three elements of sine signal are () A. Range B. Frequency C. Effective value D. Phase

The three elements of a sinusoidal signal are (a) amplitude, b) frequency and D) phase

A total of 270 students from Grade 7 of a school participated in voluntary activities. The rent of a 45 seat minibus was 250 yuan, and that of a 60 seat bus was 300 yuan,
It is known that there are more buses than minibuses, and they are just full of buses and minibuses. How many buses and minibuses do you rent? How much is the total rent?

Set cart x
60x+45（x-1）=270
60x+45x-45=270
105x=270+45
105x=315
x=3
Car 3-1 = 2
300x3 + 250x2 = 1400 yuan

If the K power of a is a zero matrix (k is a positive integer), we prove that the inverse matrix of I-A is equal to the square of I + A + A +... + the k-1 power of A

(1-A)[1+A+A^2+A^3+...+A^(k-1)]
=1+A+A^2+A^3+...+A^(k-1)-(A+A^2+A^3+...+A^k)=I
The inverse matrix of I-A is equal to the square of I + A + A +... + k-1 power of A

Complex number operation,
Why is 2 / (1 + I) ^ 2 equal to - I

2/(1+i)^2
=2/(1+2i+i^2)
=2/(1+2i-1)
=2/2i
=1/i
=-i/(i*-i)
=-i

A teacher of a school takes students to Beijing to attend a summer camp. Travel agency a says, "if the teacher buys a full ticket, the rest of the students can enjoy half price discount." travel agency B says, "including the teacher, all the students will get a 60% discount on the full ticket." if the ticket price to Beijing is 240 yuan. (1) when the student is a student, he will get a 60% discount on the full ticket______ The two travel agencies charge the same per person hour? (2) When the number of students is less than or more than how many, which travel agency is more favorable?

Suppose there are X students. (1) ∵ the two travel agencies charge the same fees, so 240 + 240 × 0.5x = (x + 1) × 240 × 0.6 to get x = 4; (2) when a travel agency is more preferential: 240 + 120x ＜ 144 (x + 1) to get x ＞ 4 when B travel agency is more preferential: X ＜ 4 answer: when the number of students is 4, the two travel agencies charge the same fees. When the number of students is more than 4, a travel agency is more preferential, when the number of students is less than 4 B travel agency is more favorable

LIM (x, y) → (0,1) (1 + XY) ^ 1 / x, please help me. Thank you

The original formula = LIM (x, y) → (0,1) (1 + XY) ^ [1 / YX · y]
=[lim(x,y)→(0,1) (1+xy)^1/yx]^[lim(x,y)->(0,1)y]
=e^1
=e

The domain of function: y = x / 3x-2

There is 3x-2 not equal to 0, so there is x not equal to 2 / 3

I only have you in my heart

My heart only you

A-1 of a + 1 is equal to?

2 / 1 - (a + 1)

Given the function f (x) = log2 (| x + 1 | + | X-2 | - M). (1) when m = 5, find the domain of definition of function f (x); (2) if the solution set of inequality f (x) ≥ 1 about X is r, find the range of value of M

(1) The answer set of the inequality is the union of the following three inequality sets: X ≥ 2x + 1 + X − 1 + X know: when m = 5, the answer set of the inequality is the set of the following three inequality sets: X ≥ 2x + 1 + X − 2 > 5, or 1 ≤ x < 2x + 1 | | |x-1 + |x-2 | 5, the solution set of the inequality is the union set of the following three inequality sets: X ≥ 3 inequality sets of the following three inequality sets of the solution sets of the following three inequality sets: X ≥ 2x ≥ 2x + 2x + 1 + 2x (2) inequality f (2) f (2) inequality f (2) f (2) f (2) inequality f (x) ≥ 1, that is | x + X + X + 1 | + | X-2| The solution set of the inequality | (x + 1) - (X-2) | = 3, the inequality | (x + 1 | + | (X-2 | > m + 2 is r, | (M + 2 ＜ 3), and the value range of M is (- ∞, 1). So the answer is (- ∞, 1)