Question

50 pontos que souber me ajude

Answer 1

Δz= 3(x+Δx)+4(y+Δy)-3x-4y
Δz=3x+3Δx+4y+4Δy-3x-4y
Δz = 3Δx+4Δy

Answer 2

$\boxed{\Delta z=f(x_o+\Delta x, y_o+\Delta y)-f(x_o,y_o)}\\ \\ f(x,y)=3x+4y\\ \\ \Delta z=3(x_o+\Delta x)+4(y_o+\Delta y)-(3x_o+4y_o)\\ \\ \Delta z=3x_o+3\Delta x+4y_o+4 \Delta y_o-3x_o-4x_o)\\ \\ \boxed{\Delta z = 3\Delta x+4\Delta y}$