Given
The value of x is 3 , y is -4 and z is 5.
Explanation
a. To find the value of the expression
[tex](x+y)^2-(x-y)^2[/tex]
Substitute the values of x and y
[tex]\begin{gathered} (3+(-4))^2-(3-(-4))^2=1-49 \\ 1-49=-48 \end{gathered}[/tex]
The answer is -48.
b. To find the value of the expression
[tex]2\left(2x+3y-4z\right)^2-xyz[/tex]
Substitute the values of x , y and z.
[tex]\begin{gathered} 2(2\times3+3(-4)-4(5))^2-3(-4)(5) \\ 2(6-12-20)^2+60 \\ 2(676)+60=1412 \end{gathered}[/tex]
The answer is 1412.
