solve by completing the square 2X^2 – 8X – 9 = 0?

Question

solve by completing the square 2X^2 – 8X – 9 = 0

Answer 1

2(x^2 - 4x - 4.5) = 0

2(x^2 - 2*2x + 2^2 - 2^2 - 4.5) = 0
2[(x - 2)^2 - 8.5] = 0

2[(x - 2 - sqrt(8.5)][(x - 2 + sqrt(8.5)] = 0

x1 = 2 - sqrt(8.5)
x2 = 2 + sqrt(8.5)

Answer 2

C'mon, you're able to do it! Given ax^2 + bx + c, whilst a = a million, complete the sq. like this: upload (b/2)^2 - (x^2 + bx + (b/2)^2) + c = (x + b/2)^2 + c If a does no longer equivalent a million it truly is somewhat trickier, however the comparable techinque. First factor out a: a(x^2 + bx/a + c/a) So complete the sq. interior the parentheses, different than now the coefficient of the 1st degree term is b/a, so which you will ought to upload (b/2a)^2: a(x^2 + bx/a + (b/2a)^2 + c/a) a((x + b/2a)^2 + c/a) a(x + b/2a)^2 + c So, i will do quantity 2: 2x^2 + 9x + a million = 0 2(x^2 + 9x/2 + a million/2) = 0 x^2 + 9x/2 + a million/2 = 0 x^2 + 9x/2 + (9/4)^2 + a million/2 = (9/4)^2 do no longer overlook to characteristic (b/2)^2 to the two factors of the equation (x + 9/4)^2 + a million/2 = (9/4)^2 (x + 9/4)^2 = (eighty one/sixteen) - (a million/2) = seventy 3/sixteen |x + 9/4| = sqrt(seventy 3/sixteen) x + 9/4 = sqrt(seventy 3)/4 x = (sqrt(seventy 3) - 9) / 4 x + 9/4 = -sqrt(seventy 3)/4 x = -(9 + sqrt(seventy 3)) / 4 So x is a member of the set {[-(9 + sqrt(seventy 3)) / 4], [(sqrt(seventy 3) - 9) / 4]}. it rather is the difficult one. I wager you're able to do the different 2.

Answer 3

2(x+1)(x-9)

Answer 4

2x^2-8x-9=0
1/2(2x^2-8x-9)
x^2-4x-9/2=0
x^2-4x+4=9/2+4
(x-2)^2=8.5
x-2=+/- 2.915
x1=-0.915
x2=4.915

Answer 5

ax^2+bx+c=o
x= (-b+sqrt (b^2-4ac) )/2a, (-b-sqrt (b^2-4ac) )/2a
a= 2 , b= -8 c=-9
x = ( 8 + sqrt(64+72)), ( 8 - sqrt(64+72))