Answer: i think its B not sure tho.
Step-by-step explanation:
Answer:
P = 12 + 5x
Step-by-step explanation:
P = a + b + c
P = 7 + (x + 4) + (4x + 1)
= 7 + x + 4 + 4x + 1
= 12 + 5x
<span>C. E(n)=5n+42
5 times the number of people + 7 times 6
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Step-by-step explanation:
The upstream speed is S / t₁, and the downstream speed is S / t₂.
If we say f is the speed of the fish in calm water, and r is the speed of the river, then:
f − r = S / t₁
f + r = S / t₂
If we say T is the time it takes to cross the river, then the speed perpendicular to the river is ℓ/T, the speed parallel to the river is r, and the overall speed is f.
Using Pythagorean theorem:
f² = (ℓ/T)² + r²
f² − r² = (ℓ/T)²
(f − r) (f + r) = (ℓ/T)²
(S / t₁) (S / t₂) = (ℓ/T)²
S² / (t₁ t₂) = (ℓ/T)²
(t₁ t₂) / S² = (T/ℓ)²
√(t₁ t₂) / S = T/ℓ
T = ℓ√(t₁ t₂) / S