Math help please, solve for x?
回答 (12)
2008-11-22 10:12 am
✔ 最佳答案
This equation cannot be solved by factor method. So use the formula:-b±√b²-4ac/2a
Here, a = 4, b=4, c = -7
On substitution in the formula,
Roots are[x=]: -1±√8/2
2008-11-22 10:03 am
4x*2+4x=7
8x+4x=7
12x=7
x=7/12
8x+4x=7
12x=7
x=7/12
2008-11-22 3:23 pm
4x^2 + 4x = 7
4x^2 + 4x - 7 = 0
x = [-b 屉(b^2 - 4ac)]/2a
a = 4
b = 4
c = -7
x = [-4 屉(16 + 112)]/8
x = [-4 屉128]/8
x = [-4 屉(2^6 * 2)]/8
x = [-4 ±2^3â2]/8
x = [-4 ±8â2]/8
x = -1/2 屉2
â´ x = -1/2 ±â2
4x^2 + 4x - 7 = 0
x = [-b 屉(b^2 - 4ac)]/2a
a = 4
b = 4
c = -7
x = [-4 屉(16 + 112)]/8
x = [-4 屉128]/8
x = [-4 屉(2^6 * 2)]/8
x = [-4 ±2^3â2]/8
x = [-4 ±8â2]/8
x = -1/2 屉2
â´ x = -1/2 ±â2
2008-11-22 12:03 pm
(-b+/- sqt (b^2 -4ac))/2a,
Here a=4,b=4,c=-7
Subtituting these values
-4+/-sqt(4^2 -4*4*-7)/2*4
-4+/-sqt(16+112)/8
-4+/-sqt(128)/8
-4+/-sqt(64*2)/8
-4+/-8sqt2/8
-4(1+/-2sqt2)/8
-1+/-2sqt2/2
-1+2sqt2/2 or -1-2sqt2/2
Here a=4,b=4,c=-7
Subtituting these values
-4+/-sqt(4^2 -4*4*-7)/2*4
-4+/-sqt(16+112)/8
-4+/-sqt(128)/8
-4+/-sqt(64*2)/8
-4+/-8sqt2/8
-4(1+/-2sqt2)/8
-1+/-2sqt2/2
-1+2sqt2/2 or -1-2sqt2/2
2008-11-22 10:20 am
the equation is a quadratic equation. There are 3 ways to solve a quadratic eq.: completing the square, factoring and the easiest and fastest way, quadratic formula. Assume we chose quadratic formula in this eq. but first we cannot use quadratic formula if it isn't arrange in the standard form: ax^2 + bx + c = 0. so, the first thing you do is to change it to the standard form. 4x^2 +4x - 7 = 0. then use QF. I hope you haven't forgot your QF.
in the end, you'll have
x = 0.91, x =-1.91
the answer is in a radical form. i use a calculator so now it's in decimal form
hope a gave you the right answer and that this would help.
in the end, you'll have
x = 0.91, x =-1.91
the answer is in a radical form. i use a calculator so now it's in decimal form
hope a gave you the right answer and that this would help.
2008-11-22 10:12 am
Make equation into a quadratic equation by sub 7 both sides
4x² + 4x = 7 sub 7 from both sides
4x² + 4x - 7 = 0
Use the Quadratic Equation at this site and work out the problem.
http://www.1728.com/quadratc.htm
4x² + 4x = 7 sub 7 from both sides
4x² + 4x - 7 = 0
Use the Quadratic Equation at this site and work out the problem.
http://www.1728.com/quadratc.htm
2008-11-22 10:10 am
4x^2+4x=7
4x^2+4x-7=0
using the quadratic formula....
(-b+/- sqt (b^2 -4ac))/2a
-4+/- sqt (16+56)
------------------------
8
-4+/- sqt (72)
------------------
8
x= 0.561 and -1.561
4x^2+4x-7=0
using the quadratic formula....
(-b+/- sqt (b^2 -4ac))/2a
-4+/- sqt (16+56)
------------------------
8
-4+/- sqt (72)
------------------
8
x= 0.561 and -1.561
2008-11-22 10:04 am
4x^2+4x=7
so
4x^2+4x-7 = 0
so use the quadratic formula to find values for x, where a=4, b=4, c=-7.
so
4x^2+4x-7 = 0
so use the quadratic formula to find values for x, where a=4, b=4, c=-7.
2008-11-22 10:04 am
subtract the 7 first then use the quadratic equation:
http://en.wikipedia.org/wiki/Quadratic_equation
You can also graph it (after subtracting the 7) and look to see where the equation crosses the x-axis (i.e. where y=0).
http://en.wikipedia.org/wiki/Quadratic_equation
You can also graph it (after subtracting the 7) and look to see where the equation crosses the x-axis (i.e. where y=0).
收錄日期: 2021-05-01 11:30:57
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081122020027AAJXDQt