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10 answers

x^2 - 7x - 8=0
A=1
B=-7
C=-8

D= B^2-4*A*C = 81
sqrt(D)=9

Formula:
x = (-B+/-sqrt(D))/(2*A)

x1 = (7+9)/2 =8
x2 = (7-9)/2 = -1

Roots are 8 and -1

2006-12-17 01:10:49 · answer #1 · answered by Som™ 6 · 0 1

rearrange the terms so that the whole system is summed to zero:

x^2 - 7x + 8 = 0

now, note the coefficients on each term, and label them from the greatest order to the least (careful with signs):

a = 1 (from 1 * x^2)
b = -7 (from -7 * x^1)
c = 8 (from 8 * x^0)

now, solve the quadratic formula for the two roots

root1 = ( -b + sqrt(b^2 - 4ac) ) / 2a
root2 = ( -b - sqrt(b^2 - 4ac) ) / 2a

in some cases you will get imaginary numbers, but that is usually ok. if the terms inside the sqrt are negative, then you will get an imaginary (complex) number

2006-12-17 01:22:40 · answer #2 · answered by otis_hobson 3 · 0 0

to make a quadratic equation

x^2 -7x -8 = 0 an obvious solution is x= -1
as the produncts of root = -8 the other root is 8

I GIVE YOU THE QUADRATIC FORMULA

x1 =( 7 + ( 49+4*8)^0.5)/2 = 8

x2 =( 7 - ( 49+4*8)^0.5)/2 = -1

2006-12-17 01:32:29 · answer #3 · answered by maussy 7 · 0 0

(x-8)(x+1)
X=8 or X=-1

2006-12-17 03:31:43 · answer #4 · answered by sweetgirl5900 2 · 0 0

x² = 7x + 8

x² - 7x - 8 = 0

- - - - - - - - -

Quadratic formula

x = - b ± √b² - 4ac/2a

x = -(-7) ± √( - 7)² - 4(1)(- 8) / 2(1)

x = 7 ± √49 - (- 32) / 2

X = 7 ± √49 + 32 / 2

X = 7 ± √81/ 2

X = 7 / 2 ± 9 / 2

X = 3.5 ± 4.5

- - - - - - - --

Solving for +

x = 3.5 + 4.5

x = 8

- - - - - - - - -

Solving for -

x = 3.5 - 4.5

x = - 1

- - - - - - - -s-

2006-12-17 03:50:58 · answer #5 · answered by SAMUEL D 7 · 0 0

x^2=7x+8
x^2-7x-8=0
using the quadratic formula ,ax^2+bx+c=0
x= (-b+(b^2-4ac)^0.5)/ 2a or x= (-b-(b^2-4ac)^0.5)/ 2a

thus, you will get your answer as
x=8 or x=1

Now, try solving the similar questions on your own to get the idea.

2006-12-17 01:27:16 · answer #6 · answered by D. Xavier 1 · 0 0

x^2 - 7x - 8 = 0
delta = 7^2 + 8 * 4 = 81
x1 = (7 + sqrt(delta))/2 = 8
x2 = (7 - sqrt(delta))/2 = -1

2006-12-17 01:11:13 · answer #7 · answered by James Chan 4 · 0 1

u don't have to it comes out
(x-1)(x+8)
x^2-1x+8x-8, which ends up as x^s-7x-8, same as x^2=7x+8.

2006-12-17 01:11:59 · answer #8 · answered by marajader2d2 3 · 0 1

one solution is -1 and the other solution is 8.

2006-12-17 04:16:23 · answer #9 · answered by wheels 2 · 0 0

a=7 b=5 c=8 so: -5 +/- (squared roots of) 25-4(7)(8) ____________________________ all divided with the help of two -5 +/- (squared roots of) 25-224 __________________________ all divided with the help of two -5 +/- (squared roots of) -199 -5 +/- i (squared roots of) 199 X= -5 + i (squared roots of) 199 ________________________ all divided with the help of two x= -5 - i (squared roots of) 199 ________________________ all divided with the help of two

2016-11-30 21:15:05 · answer #10 · answered by picart 4 · 0 0

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