Thursday

September 18, 2014

September 18, 2014

Posted by **summer** on Sunday, February 12, 2012 at 8:21pm.

I have absolutely no idea how to solve this problem.

- math -
**Reiny**, Sunday, February 12, 2012 at 10:10pmfrom the 2nd equation: y = 7-x

sub into the other

Q = 3x^2 + 4(7-x)^2)

= 3x^2 + 4(49 - 14x + x^2

= -x^2 + 196 - 56x + 4x^2

= 3x^2 - 56x + 196

The minimum of Q occurs at the vertex of the corresponding parabola

If you know Calculus ...

dQ/dx = 6x - 56 = 0 for a min of Q

6x=56

x = 56/6 = 28/3

Q = 3(28/3)^2 - 56(28/3) + 196 = -196/3

If no Calculus, then complete the square ...

Q = 3(x^2 - (56/3)x + 784/9 - 784/9) + 196

= 3( (x - 28/3)^2 - 784/9) + 196

= 3(x-28/3)^2 - 784/3 + 196

= 3(x-28/3)^2 - 196/3

so the min of -196/3 happens when x = 28/3

- math -
**grave**, Tuesday, December 10, 2013 at 9:13pmWhat is the distance between the parallel lines, whose equation are 3x + 4y = 2 and 3x + 4y = -5.

**Answer this Question**

**Related Questions**

Math Absolutely no idea - Find the absolute maximum value and the absolute ...

Calculus - Find the extreme value(s) of the function f(x)=1/(1-x^2). I tried, ...

math - Consider the initial value problem, f(x,y) = y(18.06 - y), y(0) = 12. The...

Calculus - Evaluate the integral of 4x^2(2+x^3)^9 dx. I'm supposed to use the ...

MATH - How do i solve the pair of simultaneous equations y=4-2x y=2x^2-3x+1 ?? ...

pre calc - Find the values of b such that the system has one solution. x^2 + y^2...

7th grade math Ms. Sue please - I have absolutely NO IDEA how to solve this ...

Algebra 2 - solve log2(3x-1)-log2(x-1)=log2(x+1) i have absolutely no idea how ...

math - Is 4,564,282 a prime or composite number?! Seriously, I have absolutely ...

Chem Problem - I need help solving this question, I have no idea what I'm ...