1.2
2.M=5,X = 1; M=3,X = 2; M=2,X = 4;
M=-3,X =- 1; M=- 1,X =-2; M=0,X=-4
3.6
4.40
5.3
6. Two methods
1. Backward deduction: According to the meaning of the question, the eldest daughter is divided into 1, the second son into 2, the eldest son into 4, and the mother into 8, * * * with 15.
Second, the column equation: let * * have x cows.
Judging from the meaning of the question:
1/2{ 1/2[ 1/2( 1/2-0.5)-0.5]-0.5}-0.5=0
1/ 16X = 15/ 16
X= 15
A: * * * There are 15 cows.
7. Let four numbers be x, X+7, X+ 14 and X+2 1 respectively.
X+X+7+X+ 14+X+2 1=46
X= 1
A: The four days are 1, 8, 15, 22 respectively.
8. Let these nine numbers be x, x+ 1, x+2, x+7, x+8, x+9, x+ 14, x+ 15 and x+ 16 respectively.
Then x+x+1+x+2+x+7+x+8+x+9+x+14+x+15+x+16 =17/.
X= 1 1
A: These nine days are 1 1, 12, 13, 18, 19, 20, 25, 26 and 27 respectively.
9. Let the purchase price be a, which means: (1+x%) a = (1+x%+10%) (1-8%) a.
After simplification: (1+x%) a = (0.92 x%+101.2%) a.
0.08X= 1.2
X= 1500
A: X= 1500.
10. If the original price is X yuan, then 0.9X-0.8X=2.
X=20
Answer: The original price of this 10 kg egg is 20 yuan.
Fill in the blank reference method:
1. From the meaning of the question, X+ 1=2X- 1, so X=2.
2. solution: X(M- 1)=4, and x is an integer.
So there are six possibilities.
m- 1 = 4; m- 1 = 2; m- 1 = 1; m- 1 =-4;
m- 1 =-2; M- 1=- 1
So; M=5,X = 1; M=3,X = 2; M=2,X = 4;
M=-3,X =- 1; M=- 1,X =-2; M=0,X=-4
3. from the meaning of the question: k = X.
So 2K+ 1=3.
4K+2=6 (each side multiplied by 2)
4. set a price of x yuan,
The equation is 0.9X= 1.2*30.
X=40
5. From the meaning of the question: 2N-2=N+ 1.
N=3