Wednesday

October 22, 2014

October 22, 2014

Posted by **John** on Tuesday, March 12, 2013 at 4:48am.

sqrt[(x-20)(y-x)] + sqrt[(140-y)(20-x)] + sqrt[(x-y)(y-140)] if

-40<=x<=100 and -20<=y<=200

- maths -
**Saurabh D**, Wednesday, March 13, 2013 at 1:23amLets assume that x>y

then x>-20 (as x>y minimum value of y is -20)

see the first term

sqrt[(x-20)(y-x)]

as x>-20 and x>y

the term inside the sqrt becomes negative.

Hence x!>y (not greater than y)

similarly you can prove that y is not greater than x.

Hence x=y

put x=y in the expression

only middle term is left.

sqrt[(140-y)(20-x)]

to maximise we put x=-40

sqrt[(140-(-40))(20-(-40))]

=80

hence the answer is 80 :)

- maths -
**Anonymous**, Wednesday, March 13, 2013 at 3:14amsqrt[180*60] is not 80

- maths -
**Anonymous**, Thursday, March 14, 2013 at 10:53pmWe have the limitation that -20 <= y <= 200, so we can't say that x = y = -40. Instead, we have to use x = y = -20 to maximize it, so sqrt(160 * 40) is 80.

- maths -
**Saurabh D**, Sunday, March 17, 2013 at 9:02amOh yeah!!! that's was a typo :P

**Answer this Question**

**Related Questions**

Algebra - Find the largest possible real value of \sqrt{(x-20)(y-x)} + \sqrt{(...

Math Help please!! - Could someone show me how to solve these problems step by ...

math,algebra,help - Directions are simplify by combining like terms. x radiacal ...

Math/Calculus - Solve the initial-value problem. Am I using the wrong value for ...

math,correction - simplify: sqrt ((7)/(100)) my work: 7 = 1sqrt (7) 100= 10 sqrt...

Math - How do you find a square root of a number that's not a perfect square? I'...

Mathematics - sqrt 6 * sqrt 8 also sqrt 7 * sqrt 5 6.92820323 and 5.916079783 So...

Math(Roots) - sqrt(24) *I don't really get this stuff.Can somebody please help ...

Calculus - Please look at my work below: Solve the initial-value problem. y'' + ...

Inequality - When I solve the inquality 2x^2 - 6 < 0, I get x < + or - ...