For example: a: b = (a is the ratio of the previous paragraph; B is the last term of the ratio; Is the ratio, the ratio is usually a fraction, which can be an integer or a decimal)
2. Method of finding ratio and simplifying ratio: both the former and the latter can be used. For example: =(b, d0)
3. Comparison with division: the former term of comparison is equivalent to dividend, the latter term is equivalent to divisor, and the ratio is equivalent to quotient.
For example: A: B = A ÷ B = (B0).
4. According to the relationship between fraction and division, the former term of ratio is equivalent to numerator, the latter term is equivalent to denominator, and the ratio is equivalent to the value of fraction. For example: A: B = A ÷ B = (B0)
5. The basic nature of the ratio: the first term and the second term of the ratio are multiplied or divided by the same number at the same time (except 0), and the ratio remains unchanged. For example: A: B = A: B = (B is not equal to 0)
The ratio of 1: 1, the requirement of composition ratio, and the formula of two equal ratios. 2. The basic property of proportion: the product of internal terms is equal to the product of external terms. (Cross multiplication, equal product) Need to master: According to a multiplication equation, you can write the corresponding proportion. For example: 16×5=20×4, we can get:16: 4 = 20: 54:16 = 5: 20 5: 4 = 20:16 4: 5 =/kloc. The positive proportional quotient is certain, and the inverse proportional product is certain. Step 1: Whether two known quantities are related. Step 2: How to combine the two makes sense. Step 3: Can we find the invariants? Such as: the purchase of sixth grade math books, the number of purchases and the total price paid. Known quantity and total price are two related quantities; It makes sense that the total price divided by the quantity equals the unit price. The unit price of each math book is fixed, that is, the quotient is fixed, so it is proportional. Such as the area and radius of a circle. Area and radius are two related quantities; Area divided by radius equals pi times radius. The radius changes all the time, so the product is a variable quantity. Quotient is not necessarily, so they are out of proportion. 4. The perimeter, radius or diameter of a typical supplementary circle. The square of the area is proportional to the radius of the circle. The circumference of a square is proportional to the length of its sides. A proportional rectangle has a certain circumference, length and width. A disproportionate 5. Trend chart. Positive proportion: oblique straight line, the trend is upward to the right. Inverse ratio: curve, from high to low, gradually approaching the horizontal axis. 6. Solution ratio. Basis: The basic property of proportion (the product of inner terms equals the product of outer terms) 7. The application steps of solving the ratio: examine the problem, judge what quantity is unchanged, and determine the relationship between the other two quantities. List the proportions according to the equivalence relation. Expression form: proportional X: Y = K (certain) (division formula) A: B = C: D inversely proportional x×y =k (certain) (multiplication formula) A×B = C×D 2: scale scale: the ratio of the distance on the map to the actual distance. Remember: kilometers are centimeters, and the decimal point is shifted to the right by 5 places. Centimeter kilometers, the decimal point is shifted to the left by 5 places. For example: 2.5 km = 250,000 cm.