Given the sine current I1 = 70.7sin (314t-30 °) a, I2 = 60sin (314T + 60 °) A. find the sum of the sine current I1 and I2

Given the sine current I1 = 70.7sin (314t-30 °) a, I2 = 60sin (314T + 60 °) A. find the sum of the sine current I1 and I2

If I 1 = 8 sin (W T + 90 °), I 2 = 6 sin W T, I = I 1 + I 2, then the effective value of I is
If the sine current is I1 = 8sin (ω T + 90 °), I2 = 6sin ω T, I = I1 + I2, then the effective value of I is
In RL Series sine circuit, if the power factor is known to be equal to 0, then R: XL=

10/√2
3:4

The average number of a, B and C is 8.5, of which a is twice as much as B, and C is 3.5 more than B?

Let B be X
2X+X+X+3.5=8.5*3
4X+3.5=25.5
4X=22
X=5.5
A = 5.5 * 2 = 11
B = 5.5
C = 5.5 + 3.5 = 9

If the sum of two rational numbers is negative, then the two numbers must be zero and negative. Is that right?

No, it can also have a positive number
Take a counter example
For example, 5 + (- 7) = - 2, the sum is negative, and 5 is positive

A and B deposit 200 yuan in the bank, B deposit 870 yuan, a monthly deposit of 50 yuan, B monthly deposit 120 yuan, a few months later, B deposit is a deposit
3 times

After x months, the deposit of B is three times that of A
870+120X=3(200+50X)
30X=270
X=9
Nine months later, B's deposit is three times that of a's

The curve equation represented by ρ cos ^ 2 θ = 2Sin θ is?

ρcos²θ=2sinθ
ρ²cos²θ=2ρsinθ
Let ρ cos θ = x, ρ sin θ = y,
Then x & # 178; = 2Y, X & # 178; + Y & # 178; = ρ,
That is, 2Y + Y & # 178; = ρ, ρ = (y + 1) &# 178; - 1

60 percent of a number is 120. What's the number

120÷60%
=120×100÷60
=200
This number is 200

Let the sum of all elements of n-order matrix a be zero, and the rank of a be n-1, then the general solution of linear equation AX = 0 is______ ．

The sum of elements in each row of matrix A of order n is zero , 1) t (column vector of N ones) is a solution of AX = 0. Because the rank of a is: n-1, the dimension of basic solution system is: N-R (a), so the dimension of basic solution system of a is 1, because (1, 1 T is a solution of the equation, not 0, so the general solution of AX = 0 is: K (1,1 ，1）T．

The time taken by Party A to make 90 machine parts is equal to the time taken by Party B to make 120 machine parts. It is known that Party A and Party B make a total of 35 machine parts per hour?

Let a make X machine parts per hour. The result is: 90x = 12035 − X. the solution is: x = 15

4/5x-6/7x=12!

Original form=
28x-30x=420
-2x=420
x=-210