1. The simplest common denominator of fractions 2 / x ^ 2-3x and 4x / x ^ 2-9 is () 2. Divide the fractions - 1 / (x-1) (x + 1), 2 / (x + 1) (x + 2), 3 / - (x + 2) (x-1) to get

1. The simplest common denominator of fractions 2 / x ^ 2-3x and 4x / x ^ 2-9 is () 2. Divide the fractions - 1 / (x-1) (x + 1), 2 / (x + 1) (x + 2), 3 / - (x + 2) (x-1) to get

1. The simplest common denominator of the fractions 2 / x ^ 2-3x and 4x / x ^ 2-9 is (x (x + 3) (x-3)); 2. - 1 / (x-1) (x + 1), 2 / (x + 1) (x + 2), 3 / - (x + 2) (x-1) are - 1 (x + 2) / (x-1) (x + 2), 2 (x-1) / (x-1) (x + 1) (x + 2), - 3 (x + 1) / (x-1) (x + 1) (x + 2)

The top students of Chunhui primary school take part in the school choice examination. It is known that there are 28 more girls than boys. All boys are admitted to famous schools, 34 girls are admitted to famous schools, and 42 boys and girls are admitted to famous schools. How many boys and girls take part in the school choice examination? (solving problems with algebraic method)

Suppose there are x boys and X + 28 girls, then the equation is: x + (x + 28) × 34 = 42 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 74x = 21, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp

Some math problems (tonight)
1.33,9,65,85,91,22,34,21, can you divide these eight numbers into two groups equally, so that the product of four numbers in each group is equal? Please divide one point
Can 2007 be divided into the sum of two prime numbers? Why?
3. A, B, C and D are different prime numbers. Given a + B + C = D, find the minimum value of a * b * c * D

Question 1: 33, 65, 34, 21 (group 1), 9, 85, 91, 22 (group 2)
Question 2: No, because the mantissa is 7. At least one of the 7 numbers is not prime
Question 3: the minimum of a, B and C should be 1, 3 and 7, so the minimum of a * b * c * D should be 1 * 3 * 7 * 11 = 231