7x (squared) - 8x + 3 = 0
I know you divide everything by 7 to get...
x(squared) - 8/7x + 3/7 = 0
now i don't know what to do... This is alg 2 by the way, and were are learning about "i" and so on...
2006-12-13 11:39:32 · 7 answers · asked by Determinate 2 in Education & Reference ➔ Homework Help
7x^2 - 8x + 3 = 0
x^2 - 8/7x + 3/7 = 0
Completing the square:
x^2 - 8/7x + 16/49 = -5/49
Factor
(x - 4/7)^2 = -5/49
Square root both sides
x - 4/7 = i*sqrt(5) divided by 7
final answer:
x= 4/7 + (i)sqrt(5)
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7
2006-12-13 11:45:08 · answer #1 · answered by Anonymous :) 5 · 0⤊ 0⤋
Dividing everything by 7 wouldn't help much unless you're solving it by completing the square, which is the hard way. Better to use the quadratic formula. x = (-b +/- sqrt(b2-4ac))/2a.
Substitute b for -8, a for 7, c fo 3 and you get:
x = ((8 +/- sqrt (64 -4x7x3))/2x7 = (8 +/- sqrt (-20))/14, etc,.
2006-12-13 11:47:10 · answer #2 · answered by Joni DaNerd 6 · 0⤊ 0⤋
Actually only divide by 7 if you are solving by completing the square. If you want i, use the Quadratic Formula - much more efficient.
2006-12-13 11:42:15 · answer #3 · answered by hayharbr 7 · 0⤊ 0⤋
You actually don't need to divide by 7 first. You will want to use your quadratic formula:
x= (-b +/- SQUAREROOT(b^2-4ac)) divided by 2a
**sorry it's kind of hard to type it out. http://en.wikipedia.org/wiki/Quadratic_formula This site may help you see the formula a little better.
Where your a=7, b= -8 and c=3.
When you plug those in, you will have an "i" because your squareroot part comes out to be a negative number.
**sorry it's kind of hard to type it out. http://en.wikipedia.org/wiki/Quadratic_formula This site may help you see the formula a little better.
2006-12-13 11:49:43 · answer #4 · answered by Twyster01 2 · 0⤊ 0⤋
I'm in algebra 1 and we are learning the same thing but we have to factor it then use the zero property. try that maybe it will work.
2006-12-13 11:43:19 · answer #5 · answered by Krupkake 3 · 0⤊ 0⤋
When you go to school in home room ask a friend how they did it or ask your teacher
2006-12-13 11:42:08 · answer #6 · answered by Anonymous · 0⤊ 0⤋
www.algebra.com
2006-12-13 11:43:00 · answer #7 · answered by BG 3 · 0⤊ 0⤋