Answer:
10.5 metres
Step-by-step explanation:
2 cm is equal to 3m
1 cm is equal to 1.5 m
7 cm is equal to 1.5 x 7 m which is 10.5 metres.
The actual length of the wall is 10.5 m
Write and solve an equation of ratios to answer this question:
2 cm 3 m
--------- = ---------
7 cm L
Solve this for L by inverting both sides:
7cm L
---------- = --------
and then multiplying both sides by 3m:
21
----- = L
2
I think that's the answer
The real solutions are -5, -4, 4, 5. There are no complex solutions.
The equation ...
... x^4 -41x^2 +400 = 0
can be factored as ...
... (x^2 -16)(x^2 -25) = 0
... (x -4)(x +4)(x -5)(x +5) = 0
So, all roots are real and are ...
... x ∈ {-5, -4, 4, 5}
_____
These are the values of x that make the factors zero.
