quadric equation of 3x^2+5x-8=0?
回答 (9)
2008-08-28 11:34 am
✔ 最佳答案
3x^2+5x-8=0(3x+8)(x-1)=0
3x+8=0 => x= -8/3;
x-1=0 => x=1;
Hope it helps
Bye
gilvi
2008-08-28 9:11 pm
just follow
3x^2+5x-8=0
3x^2+8x-3x-8=0
x(3x+8)-1(3x+8)=0
(3x+8)(x-1)=0
x=1, x=-8/3 answer
good luck
3x^2+5x-8=0
3x^2+8x-3x-8=0
x(3x+8)-1(3x+8)=0
(3x+8)(x-1)=0
x=1, x=-8/3 answer
good luck
2008-08-28 7:58 pm
3x^2 + 5x - 8 = 0
3x^2 + 8x - 3x - 8 = 0
(3x^2 + 8x) - (3x + 8) = 0
x(3x + 8) - 1(3x + 8) = 0
(3x + 8)(x - 1) = 0
3x + 8 =0
3x = -8
x = -8/3
x - 1 = 0
x = 1
â´ x = -8/3 , 1
3x^2 + 8x - 3x - 8 = 0
(3x^2 + 8x) - (3x + 8) = 0
x(3x + 8) - 1(3x + 8) = 0
(3x + 8)(x - 1) = 0
3x + 8 =0
3x = -8
x = -8/3
x - 1 = 0
x = 1
â´ x = -8/3 , 1
2008-08-28 6:49 pm
3x^2+5x-8=0
3x^2+8x-3x-8=0
(3x+8)(x-1)=0
3x+8=0 => x= -8/3;
x-1=0 or x=1
its simple split the middle term into two parts.
3x^2+8x-3x-8=0
(3x+8)(x-1)=0
3x+8=0 => x= -8/3;
x-1=0 or x=1
its simple split the middle term into two parts.
2008-08-28 6:41 pm
3x^2+5x-8=0
=> 3x^2 - 3x + 8x - 8 =0
=> 3x(x - 1) + 8(x - 1) = 0
=> (x -1)* (3x + 8) =0
x = 1 or -8/3
=> 3x^2 - 3x + 8x - 8 =0
=> 3x(x - 1) + 8(x - 1) = 0
=> (x -1)* (3x + 8) =0
x = 1 or -8/3
2008-08-28 6:37 pm
3x² + 5x - 8 = 0
ax² + bx + c = 0
r1,r2 = [-b ± â(b²-4ac)]/2a
[-5 ± â(5² - 4(3)(-8))] / 2(3)
(-5 ± â121) / 6
(-5 ± 11 ) / 6
Answer: -8/3, 1
ax² + bx + c = 0
r1,r2 = [-b ± â(b²-4ac)]/2a
[-5 ± â(5² - 4(3)(-8))] / 2(3)
(-5 ± â121) / 6
(-5 ± 11 ) / 6
Answer: -8/3, 1
2008-08-28 6:37 pm
x= {-5 + or - (25+96)^ 1/2} / 6 = -16/6 & +1
CHECK: 3+5-8=0
and 3(-8/3)^2 + 5(-8/3) -8=0,
Generally when you have ax^2 + bx + c =0
then x={ -b + or - (b ^2 - 4ac)^1/2} / 2a,when the equation has real solutions.
CHECK: 3+5-8=0
and 3(-8/3)^2 + 5(-8/3) -8=0,
Generally when you have ax^2 + bx + c =0
then x={ -b + or - (b ^2 - 4ac)^1/2} / 2a,when the equation has real solutions.
2008-08-28 6:36 pm
3x^2+5x-8=0
3x^2+8x-3x-8=0
x(3x+8)-1(3x+8)=0
(3x+8)(x-1)=0
x=1,-8/3
3x^2+8x-3x-8=0
x(3x+8)-1(3x+8)=0
(3x+8)(x-1)=0
x=1,-8/3
2008-08-28 6:35 pm
this factors to (x-1)(3x+8) = 0
so x-1 = 0 and 3x + 8 =0 are solutions
or x = -1 and x =-8/3
so x-1 = 0 and 3x + 8 =0 are solutions
or x = -1 and x =-8/3
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