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JEE MATHEMATICS MCQ: QUADRATIC EQUATIONS

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Application +4 | -1

If

x^2+y^2+z^2=a

, then the value of

x y+z y+z x

lies in the interval

View answer and explanation

Correct option: C

\left[\frac{-a}{2}, a\right]

The correct answer is C ([

\frac{-a}{2}, a

]) because using

(x+y+z)^2 \geq 0

and

(x-y)^2+(y-z)^2+(z-x)^2 \geq 0

allows us to find the interval for

xy+yz+zx

.

More Questions from QUADRATIC EQUATIONS

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The solution of the equation

\log _7 \log _5(\sqrt{x+5}+\sqrt{x})=0

\alpha ,\beta

are the roots of

{x^2} - 3x + a = 0,a \in R

\alpha < 1 < \beta ,

\alpha ,\;\beta

be the roots of the equation

{x^2} - px + q = 0

{\alpha _1},{\beta _1}

be the roots of the equation

{x^2} - qx + p = 0,

then the equation whose roots are

\frac{1}{{{\alpha _1}\beta }} + \frac{1}{{\alpha {\beta _1}}}\mathrm{and}\;\frac{1}{{\alpha {\alpha _1}}} + \frac{1}{{\beta {\beta _1}}},

{x^2} + 4ax + 2 > 0

for all values of

x

a

lies in the interval If

f\left( x \right) = a{x^2} + bx + c\;

\;f\left( { - 1} \right) < 1,f\left( 1 \right) > - 1,f\left( 3 \right) < - 4\;

\;a \ne 0,

then Root(s) of the equation

9{x^2} - 18\left| x \right| + 5 = 0

belonging to the domain of definition of the function

f\left( x \right) = \log \left( {{x^2} - x - 2} \right)