Question

given x= -2,y = 4 evaluate 3x² - 4y

Answer 1

x=‐2

y=4

3x²‐4y

=3(‐2)²‐4(4)

=3(4)‐4(4)

=12‐16

=‐4

Answer 2

Answer:

Evaluate the given question $3x^{2}-4y$ and apply the value of $x=-2$ and $y=4$. The final answer is $3x^{2} -4y=-4$

Step-by-step explanation:

First apply the value of $x=-2$ and $y=4$  to the given question.

That is,         $3x^{2}-4y=3(-2^{2} )-4(4)$   ---------------(1)

The value of $(-2)^{2}$ is $4$. That is, $(-2)$ × $(-2)$ $=4$.

Here we applied the following rule for minus “minus multiplied by a minus is a plus”. That is, (-) × (-) = positive (+).

Equation (1) can be written as,

                        $3(-2^{2} )-4(4)=3(4)-16$

                                               $=12-16$

Now subtract the above value $12$ and  $(-16)$.

That is,                        $12-16=(-4)$

Here $16$ is the big number. So we should subtract the above value and put a sign of big number. That's why we add the minus symbol (-) into the final answer.

Final Answer is : $3x^{2} -4y=-4$