Answer:
D
Step-by-step explanation:
using the definition of n
= 
where n! = n(n- 1)(n - 2)......× 3 × 2 × 1
here n = 7 and r = 4, hence
7
= 
= 
← cancel 3 × 2 × 1 leaving
7 = 7 × 6 × 5 × 4 = 840 → D
Answer:
15.5^2 + 14.0^ = 20.8^2
436.25 = 432.64
it is not a triangle because a+b is not = c
First we find the area of the two triangles on each side (keep in mind that they are equal/congruent to each other):
(24*10)/2 = 120 cm^2
Then you find the areas of the three rectangles that are left:
24*19 = 456 cm^2
26*19 = 494 cm^2
10*19 = 190 cm^2
Finally, to find the surface area of the prism:
120+120+456+494+190 = 1,380 cm^2
2x+5y=21, x+y=3
y=3-x
2x+5y=21
2x+5(3-x) =21
2x+15-5x=21
2x-5x+15=21
-3x+15=21
-3x=21-15
-x=6/3
-x=2
x=-2
