Question

Difficulty: EasyEvaluating Algebraic Expressions

Evaluate the algebraic expression for the given variable values.

Answer:If x=3x = -3 and y=4y = 4, the value of the expression 2x23y2x^2 - 3y is 【6】.

Answer

6
Substituting x=3x = -3 into x2x^2 gives (3)2=9(-3)^2 = 9. Multiplying by 22 yields 1818. Substituting y=4y = 4 into 3y3y gives 1212. Subtracting 1212 from 1818 gives the correct value of 66.

Step-by-Step Solution

1
Substitute the given values x=3x = -3 and y=4y = 4 into the expression 2x23y2x^2 - 3y.
2(3)23(4)2(-3)^2 - 3(4)
Replace each variable with its designated numeric value.
2
Evaluate the exponent (3)2(-3)^2.
2(9)3(4)2(9) - 3(4)
Following the order of operations (PEMDAS), exponents are evaluated before multiplication.
3
Perform the multiplication operations.
181218 - 12
Multiply 2×9=182 \times 9 = 18 and 3×4=123 \times 4 = 12.
4
Subtract the terms to find the final value.
66
Perform final subtraction: 1812=618 - 12 = 6.

Key Concept

Evaluating Algebraic Expressions with Negative Values
Estimated Time:45s
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