Question

How do you evaluate `2x^2 - 2z^4 + y^2 - x^2 + z^4` if `x = -4, y = 3, and z = 2`?

Answer 1

`9`

Explanation:

Given,

`2x^2-2z^4+y^2-x^2+z^4`

Knowing that `x=-4, y=3, z=2`, replace each variable with its appropriate number.

`=2(-4)^2-2(2)^4+(3)^2-(-4)^2+(2)^4`

Recall that a number raised to a power `n` means to multiply the number by itself `n` times. Hence,

`=2(color(red)(-4)*color(red)(-4))-2(color(blue)2*color(blue)2*color(blue)2*color(blue)2)+(color(darkorange)3*color(darkorange)3)-(color(purple)(-4)*color(purple)(-4))+(color(teal)2*color(teal)2*color(teal)2*color(teal)2)`

Simplify.

`=2(color(red)16)-2(color(blue)16)+(color(darkorange)9)-(color(purple)16)+(color(teal)16)`

`=32-32+9-16+16`

`=color(green)(|bar(ul(color(white)(a/a)color(black)9color(white)(a/a)|)))`