Mathematics
Grade6
Easy

Question

The value of x2 – 5 where x = 5 is

  1. 23    
  2. 20    
  3. 22    
  4. 10    

Hint:

This is an algebraic expression. An algebraic expression consists of two components: a variable and a constant. A variable is a quantity that doesn’t have any fixed value. It takes value according to the conditions. It is denoted by the alphabet. A constant is a quantity with a fixed value. In this question, value is assigned to the variables. We have to perform the required operations and find the final value.

The correct answer is: 20


    The given expression is x2-5.
    There is one variable and one constant in the above expression. The variable is: ‘x’. Value assigned to the variable is b = 5. We have to substitute this value and find the final value of the expression.
    There are two terms in the above expression. The first term is ‘x^2’. It means we have to multiply the variable with itself.
    The second term is constant.
    We have to first substitute the value and perform the required operations.
    To substitute the value, we have to replace x by 5. After substituting the value, we will get the following equation:
    X2-5=(5)2-5
    = (5)(5)-5
    =25-5
    =20
    Therefore, the value of equation is 20.
    So option (d), which is ‘20’ is the right option.

    We have to be careful about the order of operations. We have to substitute value of variable properly.

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