Sunday

April 20, 2014

April 20, 2014

Posted by **tommas** on Sunday, October 17, 2010 at 6:56am.

y=x^2-5x-8 at the points A and B.

the curve y=p+qx-2x^2 also passes through ponts A and B. what are the values of p and q??

helpppppplease...thanks

- math -
**Reiny**, Sunday, October 17, 2010 at 8:05amFirst, find the intersection of y = x-1 with y = x^2 - 5x - 8

that is, solve

x^2 - 5x - 8 = x - 1

x^2 - 6x - 7 = 0

(x-7)(x+1) = 0

x = -7 or x = -1

sub that back into y = x-1 to get

y = 6 or y = -2 respectively

so we have A(7,6) and B(-1,-2)

since these two points also lie on ty = p + qx - 2x^2 let's sub them in

6 = p + 6q - 98 and

-2 = p -q - 8

re-arrange these two equations and solve.

They are easy to solve as it by subtracting them, since the p's are the same.

**Related Questions**

Math - a curve is such that dy/dx=4x+7. the line y=2x meets the curve at point '...

Math - a curve is such that dy/dx=4x+7. the line y=2x meets the curve at point '...

Math - Show that the tangent to the curve 25x^5+5x^4-45x^3-5x^2+2x+6y-24=0 at ...

calculus - The line y+x=9 intersects the curve y=x^2-2x+3 at the points P and Q...

calculus - A curve passes through the point (1,-11) and it's gradient at any ...

Pure Mathematics - 1. Given that the straight line y=c-3x does not intersect the...

Calculus - Damon - Find the line which passes through the point (0, 1/4) and is ...

Algebra II - Can you make sure my Algebra II work is correct? I've done the ...

12th Grade Calculus - 1. a.) Find an equation for the line perpendicular to the ...

Calculus - Please help this is due tomorrow and I dont know how to Ive missed a ...