Answer:
a. 4r² b. 2r c. 6 cm
Step-by-step explanation:
The surface area A of the cube is A = 24r². We know that the surface area, A of a cube also equals A = 6L² where L is the length of its side.
Now, equating both expressions, 6L² = 24r²
dividing both sides by 6, we have
6L²/6 = 24r²/6
L² = 4r². Since the area of one face is L², the polynomial that determines the area of one face is A' = 4r².
b. Since L² = 4r² the rea of one face of the cube, taking square roots of both sides, we have
√L² = √4r²
L = 2r
So, the polynomial that represents the length of an edge of the cube is L = 2r
c. The length of an edge of the cube is L = 2r. When r = 3 cm.
L = 2r = 2 × 3 cm = 6 cm
So, the length of an edge of the cube is 6 cm.
Answer:
just multiply 7 by 21 and 21 by 7
like
2*21/7*21. + 10*7/21*7
41/147+ 70/147
111/147. Ans
Our discriminant is 0 so, 
has one real root.
Option C is correct.
Step-by-step explanation:
we need to find the discriminant and the number of real roots for the following equation:
The discriminant is found by using square root part of quadratic formula:
where b =12, a=4 and c=9
Putting values:
To find out the number of real roots using discriminant we have following rules:
- if discriminant b^2-4ac >0 then 2 real roots
- if discriminant b^2-4ac =0 then 1 real root
- if discriminant b^2-4ac <0 then no real roots
Since our discriminant b^2-4ac is 0 so, has one real root.
Option C is correct.
Keywords: discriminant
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