If x = 2, what is the value of 3x³ − 4x² + 5?
Answer and explanation
Correct answer: 13
Substituting x = 2 gives 3(2³) − 4(2²) + 5 = 3(8) − 4(4) + 5 = 24 − 16 + 5 = 13. Therefore, 13 is correct. Values such as 15 or 17 may result from an error in evaluating the powers or following the order of operations. Exam tip: evaluate powers first, then multiplication, and finally addition or subtraction.
Frequently asked questions
What is the correct answer to this question?
13
Why is this the correct answer?
Substituting x = 2 gives 3(2³) − 4(2²) + 5 = 3(8) − 4(4) + 5 = 24 − 16 + 5 = 13. Therefore, 13 is correct. Values such as 15 or 17 may result from an error in evaluating the powers or following the order of operations. Exam tip: evaluate powers first, then multiplication, and finally addition or subtraction.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Polynomials. Topic: Operations on real numbers and the laws of exponents.
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