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WAEC Mathematics 2020 Paper

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Question : 8

Total: 48

If x = 3 and y = -1, evaluate 2(x

^2

^3

)

24
22
20
16

Solution:

Concept:

Substitute the given values of

x

and

y

into the expression and simplify using the order of operations.

Explanation:

Given expression:

2(x^2 - y^3)

.

Substitute

x = 3

and

y = -1

:

2(3^2 - (-1)^3)

Evaluate the powers:

3^2 = 9, \quad (-1)^3 = -1

So the expression becomes:

2(9 - (-1)) = 2(9 + 1) = 2(10) = 20

Answer:

The correct answer is C. 20.

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