"Question 8 Find and correct the errors in the statement: (2x)^2 + 5x = 4x + 5x = 9x
Class 8 Factorisation Page 228"
Answers
Common errors we done by solving algebraical expression and equation:
Error 1
Coefficient 1 of a term is usually not written. So we often ignores that. But while adding like terms, we should include it in the sum.
Error 2
When we multiply the expression enclosed in a bracket by a constant (or a variable) outside, we usually applied the multiplication to first term only. This is wrong calculation. Each term of the expression has to be multiplied by the constant (or the variable).
Error 3
when we square a monomial, we usually ignored the numerical coefficient. This is wrong method. The numerical coefficient and each factor has to be squared.
Error 4
when we square a binomial, we usually do not apply the proper identity. This is wrong approach. The right identity should be used.
Error 5
While dividing a polynomial by a monomial, We usually don’t divide each term of the polynomial in the numerator by the monomial in the denominator.
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Solution:
LHS = (2x)² + 5x =4x²+5x
RHS = 4x + 5x =9x
Third = 9x
LHS≠ RHS =third part
Correct statement
(2x)²+ 5x = 4x²+5x
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Hope this will help you...