If (k=3), what is the value of (2(k+4)-k^2)?
Answer and explanation
Correct answer: 5
Substituting k=3 gives 2(3+4)-3^2. The bracket equals 7, so 2×7=14, and 3^2=9. Therefore, 14-9=5, so 5 is correct. The value 14 is only the result of the multiplication part; 9 still has to be subtracted. Exam tip: after substitution, evaluate brackets, powers, multiplication, and then subtraction in order.
Frequently asked questions
What is the correct answer to this question?
5
Why is this the correct answer?
Substituting k=3 gives 2(3+4)-3^2. The bracket equals 7, so 2×7=14, and 3^2=9. Therefore, 14-9=5, so 5 is correct. The value 14 is only the result of the multiplication part; 9 still has to be subtracted. Exam tip: after substitution, evaluate brackets, powers, multiplication, and then subtraction in order.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Algebraic expressions.
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