What is the value of the expression -3x^2y+4x when x= -4 and y=2?

Question

What is the value of the expression (-3x²y+4x) when x= -4 and y=2?

Answer 1

Let's use substitution. Since x = -4, anywhere we see an 'x', we will replace it with -4. As y = 2, anywhere we see a 'y', we will replace it with a 2.

So -3x²y + 4x becomes

= [ -3 * ( -4 )² * 2 ] + [ 4 * ( -4 )]

Following order of operations, PEMDAS, within the parentheses, we have an exponent to simplify

= [ -3 * 16 * 2 ] + [ 4 * -4 ]

= [ -96 ] + [ -16 ]

= -112

Therefore, when x = -4 and y = 2 for -3x²y + 4x, your answer is -112

Answer 2

For the values given the expression becomes -3(-4)⁴ + 4(-4)=-3*256-16=-784