Question

One root of a quadratic equation is 3 +V2. The quadratic equation is?
(a) x2- 6x - 7 = 0.
(b) x2+ 6x - 7 = 0.
(c) x2+ 6x + 7 = 0.
(d) x2- 6x + 7 = 0.

Answer 1

Answer:

2+6x−7=0

x2+6x+9−9−7=0

x2+3x+3x+9=+16

x(x+3)+3(x+3)=16

(x+3)(x+3)=16

(x+3) 2=±(4)2

x+3=±4

2×a×b=6x

2×x×b=6x(∵a=x)

b= 2x/6x

b=3

b 2=9

Taking square root on both the sides,

(Half of coefficient of x = 26

∴b=3)

If, x + 3 = 4 x +3 = - 4

x = 4 - 3 x = - 4 - 3

x = 1 x = - 7

∴ 1 and - 7 are the roots of x2+6x−7=0