tailieunhanh - Sat - MC Grawhill part 26

The practice tests are great too-a little bit harder than the real thing, as the description says, but I much prefer that to the alternative. Also, the tests "feel" much more like real test than any tests except for those in "Real SATs." For the first time in ten years, I'm excited to have a text that will actually work for my kids!! | 240 MCGRAW-HILL S SAT Lesson 2 Analyzing Problems Break Complicated Problems into Simple Ones If You Can t Find What You Want Find What You Can Analyzing is key to solving many SAT math problems. Analyzing a problem means simply looking at its parts and seeing how they relate. Often a complicated problem can be greatly simplified by looking at its individual parts. If you re given a geometry diagram mark up the angles and the sides when you can find them. If you re given algebraic expressions notice how they relate to one another. 6 feet 6 feet For a certain fence vertical posts must be placed 6 feet apart with supports in between as shown above. How many vertical posts are needed for a fence 120 feet in length You may want to divide 120 by 6 and get 20 which seems reasonable. But how can you check this without drawing a fence with 20 posts Just change the question to a much simpler one to check the relationship between length and posts. How many posts are needed for a 12-foot fence The figure above provides the answer. Obviously it s 3. But 12 6 isn t 3 it s 2. What gives If you think about it you will see that dividing only gives the number of spaces between the posts but there is always one more post than spaces. So a 120-foot fence requires 20 1 21 vertical posts. Look for Simple Relationships Once you see the parts of a problem look for simple relationships between them. Simple relationships usually lead to simple solutions. If 2x2 5y 15 then what is the value of 12x2 30y Don t worry about solving for x and y. You only need to see the simple relationship between the expressions. The expression you re looking for 12x2 30y is 6 times the expression you re given 2x2 5y. So by substitution 12x2 30y must equal 6 times 15 or 90. If you can t find what you want right away just look at the parts of the problem one at a time and find what you can. Often going step by step and noticing the relationships among the parts will lead you eventually to the answer you need. In