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
Solution:
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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