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How to Solve a Problem: Basic Tips 1)Read the problem thoroughly until you understand what is the given (data) and what you are asked to find (unknown).

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Presentation on theme: "How to Solve a Problem: Basic Tips 1)Read the problem thoroughly until you understand what is the given (data) and what you are asked to find (unknown)."— Presentation transcript:

1 How to Solve a Problem: Basic Tips 1)Read the problem thoroughly until you understand what is the given (data) and what you are asked to find (unknown). 2)Whenever possible draw a picture or make a table representing the problem, where the data and the unknowns could be represented and it shows the relation between them. 3)For some problems you should have previous knowledge of analyzing the current situation and apply the necessary formulas. 4)Use letters to represent the unknowns. Basic and simple problems usually can be solved using one unknown. 5)Try to translate the problem to one or more equations. 6)To be able to solve a problem you need to find as many equations as unknowns. 7)Solve the equation (or system of equations) for the unknown(s). 8)Check the solution found in step 7 into the problem and see whether the answer is correct or not. Then write out the answer at the end.

2 The following table contains 6 examples illustrated with different type of problems. If you want to see them all, simply just mouse click till the end, otherwise you can mouse click the specific example in the table that you prefer to see. Example 1 Example 1 (Numbers) Example 2 Example 2 (Consecutive numbers) Example 3 Example 3 (Triangle- Pythagorean) Example 4 Example 4 (Discount Price) Example 5 Example 5 (Age) Example 6 Example 6 (Velocity)

3 Ex: 1. Twice a number Is 9 more than 204 minus the number. Find the number. Twice a number is 9 more than 204 minus the number. The unknown is the number, lets call it x. Replacing the number by x the problem will look like Twice x is 9 more than 204 minus x. So, the equation associated to this problem is 2x = (204 – x) + 9 Removing the parenthesis … 2x = 204 – x +9 Isolating the x in the left side … 3x = 213 Dividing by 3 both sides… x = 71 Checking 71 as solution (in the original problem). Twice the number is 2(71) = – the number is 204 – 71 = 133 And 142 = TRUE ! Answer: The number is 71 Return to Table

4 Ex 2: The sum of three consecutive even numbers is Find the numbers. From problem (1 st number)+(2 nd number)+(3 rd. number) = 1014 We need to learn how to write three consecutive even numbers. – For instance if the first number is 22, then the second is 22+2 and the third is So, given an even number its consecutive is the given number plus 2.2. Calling x the first number. First number x (even) Second number x+2 2 more than 1 st Third number x+4 2 more than 2 nd So the associated equation is x+(x+2)+(x+4) = 1014 Removing parenthesis … x+x+2+x+4 = 1014 Collecting like terms … 3x+6 = 1014 Isolating the x … 3x = Dividing by 3 … x = 1008/3 =336 Check. First number 336 (even) Second number = 338 Third number = =1014. OK! Answer: The numbers are 336, 338, and 340. Return to Table

5 Ex 3: The length of one of the legs of a right triangle is 10 inches. The other leg is 2 less than the hypotenuse. Find the hypotenuse length. Draw right triangle where Leg 1 = 10 and length hypotenuse = x So Leg 1=10, Leg 2 = x-2, Hyp = x Pythagorean Theorem: In a right triangle: (Hyp) 2 = (leg1) 2 + (leg2) 2 So, x 2 = (x-2) 2 Expanding x 2 = x 2 –4x+4 Isolating … 4x = 104 Dividing by 4 … x = 104/4 =26 So Hyp = 26 and Leg 2 = 26-2 = 24 Checking … = OK! Answer: The hypotenuse length is 26 in. 10 x x - 2 Return to Table

6 Ex 4: The sale price of a computer is $1054 after 15% discount. Find the price before discount. Let call x the price before discount. So price before discount = x discount = 15% of x = (0.15)x sale price = 1054 We know that price before discount – = sale price Replacing … x – 0.15x = 1054 Collecting … 0.85x = 1054 Dividing by 0.85 both sides x = 1054/0.85 = 1240 Check! … 15% of 1240 = 0.15(1240) = 186 And Retail price = 1240 – 186 =1054. OK! Answer: $ 1054 is the price before the discount. Return to Table

7 Ex 5: Jon is 8 years older than Sue and Sue is 3 years younger than Frank. The sum of their ages is 98. Find the ages of each one Read the problem and realize that: Jon is 8 years older than Sue So J > S and J = S+ 8 Sue is 3 years younger than Frank. So S < F and F = S+ 8 The sum of their ages is 98. J+S+F =98 Lets x be Sues age x+8 Jons age x+3 Franks age So x+(x+8)+(x+3)=98 Removing parenthesis… x+x+8+x+3 = 98 Collecting … 3x +11= 98 Isolating … 3x = 87 Dividing by 3 … x = 29 So Sue has 29 Jon has 37 & Frank has 32 Check! … Jon is 8 years older than Sue = 8. OK! Sue is 3 years younger than Frank = 3. OK! The sum of their ages is =98. OK! Answer: John has 27, Sue 29 and Frank 32. Return to Table

8 Ex 6: The moving sidewalk in some airport is 400 ft long and moves at a speed of 4 ft/sec. If Tom can walk at a speed of 6 ft/sec, how long does it take him to walk the 400 feet using the moving sidewalk? Distance = Rate x Time Replacing … 400 = 10 t Dividing … 40 = t Answer: 40 sec Moving SidewalkNot moving Start EndEnd 400 ft 6ft/s 4ft/s Distance to be traveled 400 ft Speed of sidewalk 4 ft/sec Speed of Tom on sidewalk 6 ft/sec Total speed of Tom 10 ft/sec Time required t sec + Return to Table


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