If the quadratic equation (3sin θ) x ^ 2 - (4cos θ) x + 2 = 0 with respect to X has two real roots, find the value range of θ Don't you consider that 3sin θ is not equal to 0?

If the quadratic equation (3sin θ) x ^ 2 - (4cos θ) x + 2 = 0 with respect to X has two real roots, find the value range of θ Don't you consider that 3sin θ is not equal to 0?

The discriminant is greater than or equal to 0
16cos²θ-24sinθ>=0
2(1-sin²θ)-3sinθ>=0
2sin²θ+3sinθ-2

The fifth question on page 11 of the third grade mathematics exercise book 1

I don't know where to find any exercise book. I can't help you. I'm in the top of junior high school in math

A lighting store purchased a batch of energy-saving lamps with a total price of 400 yuan. In the process of transportation, five lamps were broken carelessly. The store sold all the remaining lamps for 4 yuan in excess of the purchase price, and then purchased another batch of these energy-saving lamps with the money obtained. The purchase price was the same as that of the last time, but the quantity purchased was 9 more than that of the last time

Let the price of each lamp be x yuan. According to the meaning of the question, the equation is given as follows: (400X − 5) · (x + 4) = (400X + 9) · X. the solution of the equation is: X1 = 10, X2 = − 807 (rounding off). It is proved that x = 10 is in line with the meaning of the question. Answer: the price of each lamp is 10 yuan

To judge whether a is a prime, why only need to judge that a cannot be divisible by the root a

Because a cannot be multiplied by two (or more) integers greater than the root a

Why to judge whether a number n is prime only need to judge whether it can be 2 to root n?
Why is it that to judge whether a number n is prime or not, we only need to judge whether it can be 2 to the root n instead of 2 to N / 2?

Hypothesis
N
There is no factor from 2 to the root n
And he has a factor m that is greater than the root n
Obviously: n / M = n (an integer), because m > root n, n

A ^ n-a can be divided by N, a is a natural number, n is a prime number, Fermat's theorem or Yang Hui's triangle reasoning
A ^ n-a can be divided by N, a is a natural number, n is prime number, n = 1 + NK + 1 is Yang Hui's triangle formula, n = 2 ^ n + NK + 1, 2 ^ n / N, so a = 3 is Fermat's theorem or Yang Hui's triangle reasoning

This is Fermat's theorem

Use 2,3,..., n-1 to remove n. if n is not divisible, then n is prime, otherwise it is composite

Prime number is defined as a natural number which can not be divisible except 1 and itself
2,3,..., n-1 is the 1 of natural number N and other natural numbers besides itself

Please write the function fun. Its function is to store all non prime numbers greater than or less than integer m into the index group of XX, and return the number of non prime numbers through K
[reference answer]
void fun(int m, int *k, int xx[])
{
int i,j,n=0;
for(i=4;i

First, let me introduce the concept of prime numbers. A prime number is an integer that can only be divisible by itself and 1. Except 2, it is odd. The algorithm is as follows: I will remove each number from 2 to I-1. If one of the numbers can be divisible by I, it means that the number is not a prime number. If there is no number that can be divisible by I, then the number is a prime number
for(j=2;j

Write the function void fun (int m, int * k, int XX [] to store all prime numbers greater than 1 and less than integer m into the XX array,
For example, M = 25, then prime number is 2,3,5,7,11,13,17,19,23, and the number is 9
Help!

void fun(int m,int*k,int xx[])
{
int i,j=0;
*k=0;
for(i=2;i

What is the integral part of the arithmetic square root of 170

13×13