Solve Grade 7 Math page 39 in Textbook 1 of Knowledge Connection provides detailed guidance on solving exercises from the final exercises of Chapter II according to the curriculum in the textbook. Students can refer to this resource to tackle exercises easily and reinforce knowledge from Chapter II.
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Grade 7 Math page 39 in Textbook 1 of Knowledge Connection
Final Chapter II Exercise
Solve Exercise 2.27 Page 39 Math Textbook Grade 7
Problem:
Find the sum of the two rounded decimal numbers.
Solution Guide:
+ Use a handheld calculator to calculate a, b. Round a, b to the first decimal place.
+ Calculate the sum a + b
Answer:
We have: a = 1.414...; b = 2.23606...
Rounding a, b to the first decimal place, we get: a ≈ 1.4; b ≈ 2.2.
The sum of the two rounded decimal numbers is: 1.4 + 2.2 = 3.6.
2. Solve Exercise 2.28 Page 39 Math Textbook Grade 7
Problem: Use a measuring tape with markings to measure the length of the folded road ABC in Figure 2.8 (in centimeters, rounded to the first decimal place). Compare the result with Exercise 2.27.
Solution Guide:
Use the measuring tape to measure the lengths of segments AB and BC.
Calculate the length of the folded road ABC = AB + BC.
Answer:
We have: AB ≈ 2.2(cm); BC = 1.4(cm)
So the length of the folded road ABC is: 2.2 + 1.4 = 3.6 (cm).
This result matches the one in Exercise 2.27
3. Solve Exercise 2.29 Page 39 Math Textbook Grade 7
Problem: Divide a 10 m long copper wire into 7 equal segments.
a) Calculate the length of each wire segment, write the result in the form of an infinitely repeating decimal.
b) Use 4 of the received wire segments to form a square. Let C be the perimeter of that square. Find C by two methods and compare the results:
Method 1: Use a measuring tape with markings to measure, take the exact measurement to the nearest centimeter.
Method 2: Calculate, write the result in decimal form with an accuracy of 0.005.
Solution Guide:
a) The length of each wire segment is the result of dividing 10 by 7.
b) Calculate using both methods above
Method 1: Measure each side of the square. Perimeter of the square = Length of one side x 4.
4. Solve Exercise 2.30 Page 39 Math Textbook Grade 7
Problem: a) Given two real numbers a = -1.25 and b = -2.3. Compare a and b, |a| and |b|.
b) We observe that among two negative decimal numbers, the one with the greater absolute value is smaller.
Apply this observation to compare -12.7 and -7.12.
Solution Guide:
a) + Compare two negative decimal numbers;
+ Calculate |a| and |b| then compare.
b) Find the absolute values of the two numbers, compare the two absolute values, and conclude.
Answer:
5. Solve Exercise 2.31 Page 39 Math Textbook Grade 7
Problem: Given two real numbers a = 2.1 and b = −5.2.
a) What observation do you have about the products of a.b and −|a|.|b|?
b) Ta có cách nhân hai số khác dấu như sau: Muốn nhân hai số khác dấu ta nhân các giá trị tuyệt đối của chúng rồi đặt dấu "− " trước kết quả.
Apply the above rule to calculate (−2.5) * 3
Solution Guide:
a) Calculate the product of a.b
Calculate -|a|.|b|
b) Use the observation above.
Answer:
a) We have: a.b = 2.1 * (-5.2) = -10.92
|a| = 2.1; |b| = 5.2 ⇒ −|a|.|b| = −2.1 * 5.2 = −10.92
Observation: a.b = -|a|.|b|
Given: -2.5 and 3 have opposite signs, and |−2.5| = 2.5; |3| = 3, so (−2.5) * 3 = − (2.5 * 3) = −7.5.
Presented here is the solution to Grade 7 Math page 39 exercise 1 from the Knowledge Connection book. This serves as a valuable resource for the final exercise of Chapter II. It is hoped that it assists students in studying easily and effectively.
Next Assignment:
- Grade 7 Math page 45 exercise 1 from the Knowledge Connection book - Exercise 8: Special Position Angles. Bisector of an angle
- Grade 7 Math page 49 exercise 1 from the Knowledge Connection book - Exercise 9: Parallel Lines and Recognition Signs
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