Question

help me to solve this question. class 10 .plz don't post useless answer ​

Answer 1

Answer :

Compare given quadratic equation x² + kx + 4 = 0 ,

with ax² + bx + c , we get ,

• a = 1 , b = k , c = 4

A/c to discriminant formula , i.e.,

" The quadratic equation has two equal roots

if discriminant is equals to zero. "

⇒ b² - 4 ac = 0

⇒ k² - 4 (1) (4) = 0

⇒ k² - 16 = 0

⇒ k² = 16

⇒ k = ±4

So , for k = ±4 , the quadratic equation  x² + kx + 4 = 0

has two equal roots.

Answer 2

✯✯ QUESTION ✯✯

For what value of k ,the quadratic eqaution whose roots are equal :. x²+kx+4=0..

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✰✰ ANSWER ✰✰

$\longmapsto\tt{{x}^{2}+kx+4=0}$

➙Now , Comparing the equation with x²-kx+4 : -

• a = 1
• b = -k
• c = 4

➥Now ,

$\longmapsto\tt{{b}^{2}-4ac=0}$

➜Putting Values : -

$\longmapsto\tt{{-k}^{2}-4(1)(4)=0}$

$\longmapsto\tt{{k}^{2}-16=0}$

$\longmapsto\tt{{k}^{2}=\sqrt{16}}$

$\red\longmapsto\:\large\underline{\boxed{\bf\green{k}\purple{=}\orange{4\:or\:(-4)}}}$

☛So , The value of k is 4 or -4.....