Question

2+4 = 1 - (b) x² – 5x + 4 gives (-3)2 – 5 (-3) + 4 = 9 - 15+4 = -2 (C) x2 + 5x gives (-3)2 + 5(-3) = - 9 - 15 =- 24 -​

Answer 1

Answer:

An equation is a mathematical statement with an 'equal to' symbol between two algebraic expressions that have equal values.

a) x2+ 5x + 4 gives (-3)2 + 5(-3) + 4 = 9 + 2 + 4 = 15

For x = -3

L.H .S = x2 + 5x + 4

= (-3)2 + 5(-3) + 4

= 9 -15 + 4

= 13 -15

= -2

But RHS is given as 15

Thus, L.H.S ≠ R.H.S

The correct statement is x2+ 5x + 4 gives (-3)2 + 5(-3) + 4 = 9 -15 + 4 = -2

(b) x2 - 5x + 4 gives (-3)2 - 5(-3) + 4 = 9 - 15 + 4 = -2

For x = -3

x2 - 5x + 4

= (-3)2 - 5(-3) + 4

= 9 +15 + 4

= 28

But, RHS is given as -2

Thus, L.H.S ≠ R.H.S

The correct statement is x2 - 5x + 4 gives (-3)2 - 5(-3) + 4 = 9 + 15 + 4 = 28

(c) x2 + 5x gives (-3)2 + 5(-3) = - 9 - 15 = -24

For x = - 3

x2 + 5x

= (-3)2 + 5(-3)

= 9 -15

= - 6

But, RHS is given as -24

Thus, L.H.S ≠ R.H.S

The correct statement is x2 + 5x gives (-3)2 + 5(-3) = 9 - 15 = - 6

☛ Check: NCERT Solutions for Class 8 Maths Chapter 14

Video Solution:

Find and correct the errors in the following mathematical statement. Substituting x = -3 in (a) x²+ 5x + 4 gives (-3)² + 5(-3) + 4 = 9 + 2 + 4 = 15 (b) x² - 5x + 4 gives (-3)² - 5(-3) + 4 = 9 - 15 + 4 = -2 (c) x²+ 5x gives (-3)² + 5(-3) = -9 - 15 = -24

Class 8 Maths NCERT Solutions Chapter 14 Exercise 14.4 Question 10

Summary:

The errors in the following mathematical statement are found by substituting x = -3 (a) x2+ 5x + 4 gives (-3)2 + 5(-3) + 4 = 9 + 2 + 4 = 15 (b) x2 - 5x + 4 gives (-3)2 - 5(-3) + 4 = 9 - 15 + 4 = -2 (c) x2 + 5x gives (-3)2 + 5(-3) = -9 - 15 = -24. The corrected statements are (a) x2+ 5x + 4 gives (-3)2 + 5(-3) + 4 = 9 -15 + 4 = -2 (b) x2 - 5x + 4 gives (-3)2 - 5(-3) + 4 = 9 + 15 + 4 = 28 (c) x2 + 5x gives (-3)2 + 5(-3) = 9 - 15 = - 6

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