There are 20 questions in total. 3 points will be deducted for each mistake or not. Liu Gang got 60 points There are 20 questions in total. 3 points will be deducted for each wrong question or not. Liu Gang got 60 points. How many questions did he do right?

There are 20 questions in total. 3 points will be deducted for each mistake or not. Liu Gang got 60 points There are 20 questions in total. 3 points will be deducted for each wrong question or not. Liu Gang got 60 points. How many questions did he do right?

20x5 = 100 (min)
100-60 = 40 (points)
Wrong: 40 ÷ (5 + 3) = 5 (TAO)
Right: 20-5 = 15

Ten simple arithmetic exercises in grade five

1.99/10+1/10=
2.101/50-1/50=
3.99/33=
4.7200/45/2=
5.1800/5/2=
6.1000/125/8=
7.200/4/25=
8.360/6/6=
9.4800/60/8=
10.800/2/40=

The nature of division

The method of matching is as follows
4.5×0.4+4.5×0.3＋4.5×0.3＝4.5×﹙0.4+0.3+0.3）=4.5
0.98×10＋0.98×5＋0.98×5+0.02×1=0.98×（10+5+5）+0.02×20＝0.98×20+0.02×20=(0.98+0.02)×20=20
The nature of subtraction:
3698-687-11=3698-（687+11）=3600
2999-1001-1998=2999-（1001+1998）=0
The nature of division:
1000÷8÷125=1000÷﹙8×125﹚=1000÷1000=1
2002÷7÷11÷13=2002÷﹙7×11×13﹚=2002÷1001=2

60 questions in ten minutes for sixth grade fraction division

1. 3/7 × 49/9 - 4/3
2. 8/9 × 15/36 + 1/27
3. 12× 5/6 – 2/9 ×3
4. 8× 5/4 + 1/4
5. 6÷ 3/8 – 3/8 ÷6
6. 4/7 × 5/9 + 3/7 × 5/9
7. 5/2 -（ 3/2 + 4/5 ）
8. 7/8 + （ 1/8 + 1/9 ）
9. 9 × 5/6 + 5/6
10. 3/4 × 8/9 - 1/3
11. 7 × 5/49 + 3/14
12. 6 ×（ 1/2 + 2/3 ）
13. 8 × 4/5 + 8 × 11/5
14. 31 × 5/6 – 5/6
15. 9/7 - （ 2/7 – 10/21 ）
16. 5/9 × 18 – 14 × 2/7
17. 4/5 × 25/16 + 2/3 × 3/4
18. 14 × 8/7 – 5/6 × 12/15
19. 17/32 – 3/4 × 9/24
20. 3 × 2/9 + 1/3
21. 5/7 × 3/25 + 3/7
22. 3/14 ×× 2/3 + 1/6
23. 1/5 × 2/3 + 5/6
24. 9/22 + 1/11 ÷ 1/2
25. 5/3 × 11/5 + 4/3
26. 45 × 2/3 + 1/3 × 15
27. 7/19 + 12/19 × 5/6
28. 1/4 + 3/4 ÷ 2/3
29. 8/7 × 21/16 + 1/2
30. 101 × 1/5 – 1/5 × 21
1. Mental arithmetic
(1)58+42= (2)87－45= (3)125×8=
(4)50×12= (5)804÷4= (6)134＋66=
(7)1000－98= (8)720÷5= (9)0÷47=
2. First fill in the operation order of the following questions, and then calculate the number
(1)168+36－36+32=
(2)153－5×14+83=
(3)50×5÷50×5=
3. Judgment: mark "√" for right and "×" for wrong
(1) 13 × 15 and 15 × 13 have the same meaning
(2) The calculation result of 3000 ／ 425 ／ 8 must be less than that of 3000 ／ (425 × 8). ()
(3) The product of two factors is 800. If one factor is constant and the other factor is reduced by 20 times, then the product is 40
(4) Formula: "750 △ 25 + 35 × 2" means the quotient of 750 divided by 25; plus 2 times of 35, what is the sum
(5)24×25=6×4×25=6+100=106( )
4. Simple calculation method
(1)3786－499
(2)32×25×125
(3)1653－338－662
(4)7987+350+2013+450
(5)38×38+62×38
(6)452+99×452
(7)201×79
(8)50×125×4×8
5. Calculate the following questions:
(1)340×(120－40÷8)
(2)45×(720－1957÷19)
(3)86+[4500+(2088÷36)÷2]
(4)396×[74－(4875÷15－13×21)]
(5)[1054－(174－168)]÷8
(6)6048÷[(107－99)×9]
6. Use the comprehensive formula
(1) What is the quotient of 42 minus 28 divided by 14?
(2) What's the sum of 840 minus 480 divided by 240, plus 162?
(3) 258 plus the sum of 42 times 185 minus 158, what's the product?
(4) 1080 minus the product of 6 and 12, and then divided by 12, what's the quotient?
(5) Subtract the product of 60 and 80 from 6000, and divide the difference by 120. What's the quotient?
(6) How much more is the product of 12, 18 and 20 than their sum?
The calculation is simple
408－12×24 （46＋28）×60 42×50－1715÷5
32＋105÷5 （108＋47）×52 420×（327－238）
(4121+2389)÷7 671×15-974 469×12+1492
405×(3213-3189) 5000-56×23 125×(97-81)
6942+480÷3 304×32-154 20+80÷4-20＝
100÷（32-30）×0＝ 25×4-12×5＝
70×〔（42-42）÷18〕＝ 75×65+75×35＝
Calculate the following questions in a simple way
1、89+124+11+26+48 2、875-147-23
3．25×125×40×8 4、147×8+8×53
5、125×64 6、0.9＋1.08＋0.92＋0.1
Calculation by simple method
①89+124+11+26+48 ②875-147-23
③147×8+8×53 ④125×64
Calculate the following questions
1．280＋840÷24×5 2．85×(95－1440÷24)
3．58870÷(105＋20×2) 4．80400－(4300＋870÷15)
5．1437×27＋27×563 6．81432÷(13×52＋78)
7．125×(33－1) 8．37.4－(8.6＋7.24－6.6)
Calculation. (1 ∶ 1)
（1）156×107-7729 （2）37.85-（7.85+6.4）
（3）287×5+96990÷318 （4）1554÷[（72-58）×3]
Out of form calculation
2800÷ 100＋789 （947－599）＋76×64
1．36×(913－276÷23) 2．(93＋25×21)×9
3．507÷13×63＋498 4．723－(521＋504)÷25
5．384÷12＋23×371 6．(39－21)×(396÷6)
（1）156×[(17.7-7.2)÷3] （2）[37.85-（7.85+6.4）] ×30
（3）28×(5+969.9÷318) （4）81÷[（72-54）×9]
57×12－560÷35 848－640÷16×12
960÷（1500－32×45） [192－（54＋38）]×67
138×25×4 (13×125)×(3×8) (12+24+80)×50 704×25 25×32×125 32×(25+125)
178×101－178 84×36+64×84 75×99+2×75 83×102－83×2 98×199
123×18－123×3+85×123 50×(34×4)×3 25×（24+16） 178×99+178
79×42+79+79×57 7300÷25÷4 8100÷4÷75 75×27+19×2 5 31×870+13×310
4×(25×65+25×28) 138×25×4 (13×125)×(3×8) (12+24+80)×50
25×32×125 32×(25+125) 102×76 58×98
178×101－178 84×36+64×84 75×99+2×75 83×102－83×2
98×199 123×18－123×3+85×123 50×(34×4)×3 25×（24+16）
178×99+178 79×42+79+79×57 7300÷25÷4 8100÷4÷75

Let a, B, C be three real numbers, and 1 / A + 1 / B + 1 / C = 1 / A + B + C. It is proved that at least one of a, B, C is equal to 1

Is it 1 / A + 1 / B + 1 / C = 1 / (a + B + C)? Otherwise, both sides can subtract 1 / a at the same time and become 1 / B + 1 / C = B + C ∵ 1 / A + 1 / B + 1 / C = 1 / (a + B + C), the general differentiation is simple: ABC = (a + B + C) & sup2 ≥ 0. That is to say, at least one number of a, B and C is not less than zero! ∵ if: a < 0, B < 0, C < 0, then ABC < 0

The base of triangle and parallelogram are equal, and the area is also equal. It is known that the height of parallelogram is 8 cm, and the height of triangle is ()
A. 8 cm B, 4 cm C, 16 cm D, 12 cm

C. 16 cm

Given that the point P is a moving point on the parabola y2 = 2x, a Y-axis perpendicular PM is made through the point P, the perpendicular foot is m, and the coordinate of point a is a (72,4), then the minimum value of | PA | + | PM | is ()
A. 112B. 4C. 92D. 5

Parabolic equation is y2 = 2x \\\\\\\\\124124124124\124124\124\\124\124\\124\\\\124\\\124\\124\\\\124\\\\\\\\\\\\\\\\124e + | PF | = | AF | P point satisfies | PA | + | PF | ≥ | AF |, if and only if point P falls On the line AF, the minimum value of | PA | + | PF | = | AF | is (72 − & nbsp; 12) 2 + (4 − 0) & nbsp; 2 & nbsp; = 5, and the minimum value of | PA | + | PM | is | PA | + | PN | - 12 = | PA | + | PF | - 12 = 92, so select C

Factorization 5a-8a2 + 42

Cross method
-8 21
1 2 → -8*2+1*21=5
So the original formula = (- 8A + 21) (a + 2)

AB is the diameter of circle O, C is a point on circle O, the tangent of AD and passing through point C is perpendicular to D, the bisector angle dab of AC is proved

Because CD is tangent to a circle
So OC vertical CD
Because ad vertical CD
So ad / / OC
So angle DAC = angle ACO
Because angle ACO = angle Cao
So angle DAC = angle Cao
AC bisector DAB

The straight line MX + y-m, no matter what real number m goes to, has a straight line passing through a fixed point

mx+y-m=0
m(x-1)=-y
If X-1 = - y = 0, then M holds regardless of its value
Here x = 1, y = 0
So the straight line must pass the fixed point (1,0)