Solving Exercise 5 Page 74 Math 4 Textbook

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Solving exercise 5 on page 74 SGK Math 4 in Practice, Surface area S of a rectangle with length a and width b with a clear and detailed solution system, will be a useful study material in the practice and reinforcement of knowledge.

Guidance for solving exercise 5 on page 74 SGK Math 4

Problem statement:
The surface area S of a rectangle with length a and width b is calculated using the formula:
S = a x b (a, b in the same unit of measurement)
a) Calculate S, given:
a = 12cm, b = 5cm
a = 15m, b = 10m
b) If the length is doubled and the width remains the same, how many times does the area of the rectangle increase?

Solution Method:
a) Apply the formula: S = a x b, substitute the given values of a, b into the formula one by one, calculate carefully to find the correct answer.
b) When the length a is doubled, the new length will be a x 2 => Apply the method of calculating the area of a rectangle by multiplying length with width and then conclude.

Answer:
a) For a = 12cm, b = 5cm then S = 12 x 5 = 60 (cm²)
For a = 15m, b = 10m then S = 15 x 10 =150 (m²)
b)
The area of the new rectangle is:
a x 2 x b = (a x b) x 2 = S x 2
So when the length is doubled and the width remains the same, the area of the rectangle increases by 2 times.

The section solving exercise page 74 math 4, Practice includes Z exercises, Next, solving exercise 5 page 74 SGK math 4. Mytour suggests answers and detailed solving methods for Solving Exercise 1 Page 74 Math 4, Solving Exercise 2 Page 74 Math 4, Solving Exercise 3 Page 74 Math 4 and Solving Exercise 4 Page 74 Math 4, students need to grasp the knowledge of this lesson.

Frequently Asked Questions

What is the formula for calculating the surface area of a rectangle?

The surface area S of a rectangle is calculated using the formula S = a x b, where a is the length and b is the width, both in the same unit of measurement.

How do you calculate the area of a rectangle with specific dimensions?

To calculate the area, substitute the values into the formula. For example, with a = 12cm and b = 5cm, the area S is 12 x 5, which equals 60 cm².

What happens to the area if the length of a rectangle is doubled?

Yes, when the length is doubled while keeping the width the same, the area of the rectangle increases by 2 times, as shown by the formula S x 2.

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