Question Details

If ax² + 2hxy + by² = 1, then dy/dx equals

Options

A

hx+by/ax+by

B

ax+by/hx+by

C

ax+hy/hx+hy

D

−(ax+hy)/hx+by

Correct Answer :

−(ax+hy)/hx+by

Solution :

The correct option is: −(ax+hy)/hx+by

To find the derivative dydx of the given implicit function, we perform implicit differentiation with respect to x on both sides of the equation:

ax2+2hxy+by2=1

Differentiating each term term-by-term with respect to x:

1. The derivative of ax2 with respect to x is:
ddx(ax2)=2ax

2. For the term 2hxy, we use the product rule ddx(uv)=udvdx+vdudx:
ddx(2hxy)=2h[xdydx+y(1)]=2hxdydx+2hy

3. For the term by2, we use the chain rule:
ddx(by2)=2bydydx

4. The derivative of the constant on the right-hand side is:
ddx(1)=0

Combining all the differentiated terms, we get:
2ax+2hy+2hxdydx+2bydydx=0

We can divide the entire equation by 2 to simplify it:
ax+hy+hxdydx+bydydx=0

Now, group the terms containing dydx on one side and move the other terms to the right side:
(hx+by)dydx=(ax+hy)

Solving for dydx, we divide both sides by (hx+by):
dydx=(ax+hy)hx+by

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