Q. A curve is defined by the parametric equations x(t)=−4sin(−5t) and y(t)=−3e−8t. Find dxdy.Answer:
Find dtdx: To find dxdy for parametric equations, we need to find dtdy and dtdx separately and then divide dtdy by dtdx.
Find dtdy: First, we find dtdx. The derivative of x(t)=−4sin(−5t) with respect to t is dtdx=−4×−5×cos(−5t)=20cos(−5t), since the derivative of sin(u) with respect to u is cos(u) and we apply the chain rule for the inner function −5t.
Calculate dxdy: Next, we find dtdy. The derivative of y(t)=−3e−8t with respect to t is dtdy=−3×−8×e−8t=24e−8t, since the derivative of eu with respect to u is eu and we apply the chain rule for the inner function −8t.
Simplify dxdy: Now we have dtdx=20cos(−5t) and dtdy=24e−8t. To find dxdy, we divide dtdy by dtdx: dxdy=dtdxdtdy=20cos(−5t)24e−8t.
Simplify dxdy: Now we have dtdx=20cos(−5t) and dtdy=24e−8t. To find dxdy, we divide dtdy by dtdx: dxdy=dtdxdtdy=20cos(−5t)24e−8t.Simplify the expression for dxdy: dxdy=2024⋅cos(−5t)e−8t=56⋅cos(−5t)e−8t.
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