NCERT Class-8 Maths Factorisation Chapter-14.4

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asked Dec 27, 2017 in Mathematics by Golu (37,045 points) 19 145 413

Find and correct the errors in the following mathematical statements:

Question 1: 4(x – 5) = 4x – 5

Question 2: x(3x + 2) = 3x2 + 2

Question 3: 2x + 3y = 5xy

Question 4: x + 2x + 3x = 5x

Question 5: 5y + 2y + y – 7y = 0

Question 6: 3x + 2x = 5x2


Question 7: (2x)2 + 4(2x) + 7 = 2x2 + 8x + 7

Question 8: (2x)2 + 5x = 4x + 5x = 9x

Question 9: (3x + 2)2 = 3x2 + 6x + 4​

1 Answer

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answered Dec 27, 2017 by Ankit Agarwal (28,847 points) 7 31 67
selected Dec 27, 2017 by Golu
 
Best answer

Question 1: 4(x – 5) = 4x – 5

Answer: 4(x – 5) = 4x – 20

Question 2: x(3x + 2) = 3x2 + 2

Answer: = 3x2 + 2x

Question 3: 2x + 3y = 5xy

Answer: 2x + 3y
Here; x and y are as different as chalk and cheese and hence cannot be added together.

Question 4: x + 2x + 3x = 5x

Answer: = 6x
It is like adding one apple, two apples and three apples.

Question 5: 5y + 2y + y – 7y = 0

Answer: = y

Question 6: 3x + 2x = 5x2

Answer: = 5x


Question 7: (2x)2 + 4(2x) + 7 = 2x2 + 8x + 7

Answer: = 4x2 + 8x + 7

Question 8: (2x)2 + 5x = 4x + 5x = 9x

Answer: 4x2 + 5x

Question 9: (3x + 2)2 = 3x2 + 6x + 4

Answer: Using (a + b)2 = a2 + 2ab + b2;
= 9x2 + 12x + 4

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