Pls answer these i dont know how it is or whats the answer

9) A. -4x + y + 6z

10) A. 8x² - x - 2

Step-by-step explanation:

9)

(2x + 5y - z) + (-6x - 4y + 7z)

2x + 5y - z - 6x - 4y + 7z

-4x + y + 6z

10)

(3x² - 5x - 6) + (5x² + 4x + 4)

8x² - x - 2

U can use math-way too

The calculation of the area of the triangle is incorrect

Step-by-step explanation:

To find the surface are of the net for the polyhedron, each area of the net will be calculated. There are 2 rectangles, 1 square, and 2 triangles that made up the net of the polyhedron.

To find out which calculation is incorrect, let's do our own calculation and compare with what Jada has:

Area of rectangle = lenght * width

Area of rectangle with lenght: 5 cm, width: 4cm

Area = 5*4 = 20 cm²

Area of square with side: 4 cm,

Area = 4² = 16 cm²

Area of rectangle with lenght: 4 cm, width: 3cm

The 2 triangles have the same dimensions:

Height = 3 cm

Base = 4 cm

Area of triangle = ½*base*height

Area of each triangle = ½*4*3 = 2*3 = 6 cm²

This is different from what Jada calculated. Jada's calculation for the area of each of the triangles is incorrect. The area should be 6 cm² not 12 cm².

Surface area of the net = 20 + 16 + 12 + 2(6) = 60 cm²