Mark H. answered • 10/30/19
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Distance = Velocity * Time ---> d = v * t
For a problem like this, the net velocity is the sum of that of the boat and of the river. Let's call them vb and vr.
Since there are 2 unknowns, we need 2 equations:
Downstream: v = vb + vr, so d = t (vb + vr). Plug in the given values for d and t:
210 = 6*(vb + vr)
Upstream: same logic, but v = vb - vr, so:
210 = 42*(vb - vr)
Solve the pair of equations by one of the regular methods
Mark H.
Your question is how to solve the pair of equations? First, expand each one. Next, multiply the 1st one by 7. You will then have equal and opposite values for the vr term. Add the 2 equations, and solve for vb. Then substitute in either equation to find vr.
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10/31/19
SETH D.
i need it in solving system of linear equations10/30/19