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# Math help with graphs?

The secant y = 0.2x + 1 crosses the curve y = x^2 - 0.8x - 100

What is the equation for the tangent to the curve that is parallel with the secant?

I'm so confused. Can someone help me solve this?

### 1 Answer

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- Wayne DeguManLv 73 weeks agoFavorite Answer
For the curve, dy/dx = 2x - 0.8

The secant has gradient 0.2, so we require when:

2x - 0.8 = 0.2

so, x = 0.5

Then, y = (0.5)² - 0.8(0.5) - 100

so, y = -100.15

Hence, equation is y - (-100.15) = 0.2(x - 0.5)

Then, y + 100.15 = 0.2x - 0.1

i.e. y = 0.2x - 100.25

:)>

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