Question

If the roots of the quadratic 2x2

+ kx + 18 = 0 are equal then the value of ‘k’ is

(A) 4 (B) –4 (C) ± 12 (D) ± 16​

Answer 1

Step-by-step explanation:

Given -

If the roots of the quadratic equation 2x² + kx + 18 = 0 are equal

To Find -

Value of k

As we know that :-

• D = b² - 4ac = 0

here,

a = 2

b = k

c = 18

» b² - 4ac = 0

» (k)² - 4×2×18 = 0

» k² = 144

» k = √144

• » k = ± 12

Hence,

The value of k is ± 12

Formula Used :-

• D = b² - 4ac

Some related formulas :-

• x = -b ± √b² - 4ac/2a

Answer 2

$\large{\boxed{\underline{\underline{\bf{\red{Answer:-}}}}}}$

$\implies$ k = -,+ 12

$\large\underline\mathrm{Given:-}$

• the roots of the quadratic 2x² + kx + 18 = 0 are equal.

$\large\underline\mathrm{To \: find}$

• Value of k ?

$\large\underline\mathrm{Using \: the \: quadratic \: formula:-}$

• D = b² - 4ac = 0

$\large\underline\mathrm{Then,}$

$\implies$ a = 2

$\implies$ b = k

$\implies$ c = 18

$\large\underline\mathrm{Solution}$

$\implies$ b² - 4ac = 0

$\implies$ (k)² - 4 × 2 × 18 = 0

$\implies$ k² = 144

$\implies$ k = √144

$\implies$ k = -,+ 12

$\large\underline\mathrm{Hence,}$

$\large\underline\mathrm{The \: value \: of \: k \: is \: +12, \: -12.}$

$\large\underline\mathrm{Hope \: it \: helps \: you \: plz \: mark \: me \: brainlist}$