Question

answer both ques pls

Answer 1

$x = 3$
${x}^{3} + 2 {x}^{2} + kx + 3 = 21$
${3}^{3} + 2( {3})^{2} + 3(k) + 3 = 21$
$27 + 18 + 3k + 3 = 21$
$3k = 21 - 48$
$k = - 27 \div 3$
$k = - 9$

Hope it helps you!!

Answer 2

HELLO DEAR,


(1)



given that:-

x= -3

x³+2x²+kx+3=21

put the value of x in the Equation


we get,

3³ + 2×3²+ K×3+3=21

=> 3k=21-27-18-3

=> 3k=-27

=> k=-27/3

=> k= -9











(2)

given that:-

(a-b)x+(a+b)y=a²-b²-2ab --------------(1)

(a+b)(x+y)=a²+b²

=> (a+b)x + (a+b)y = a²+b² ---------------(2)

from--(1) and--(2)

(a-b)x+(a+b)y=(a²-b²-2ab)
(a+b)x + (a+b)y =( a²+b²)
(-)..........(-)................(-)
___________________________
(a-b)x- (a+b)x = a²-b²-2ab-( a²+b²)

=> ax-bx-ax-bx=a²-a²-b²-b²-2ab

=> -2bx= -2b²-2ab

=> -bx=-b²-ab

= > x=(a+b) put in ---(1)

we get,

(a-b)x+(a+b)y=a²-b²-2ab

=> (a-b)(a+b)+(a+b)y=a²-b²-2ab

=> a² - b²+ (a+b)y =a²-b²-2ab

=> (a+b)y =a²-b²-2ab-a²+b²

=> (a+b)y = -2ab

= > y= -2ab/ (a+b)

I HOPE ITS HELP YOU DEAR,
THANKS