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please help!! i just need the answer and the workings please. everything i've done just doesnt seem to work, where am i going wrong!!!

2006-11-16 07:14:35 · 11 answers · asked by im_a_mouldy_cheesecake 1 in Science & Mathematics Mathematics

ok i messed up...written the question wrong.
y = x^2 + x - 6 and y = 2x - 1

2006-11-16 07:21:13 · update #1

11 answers

Substitute 2x-1 for y in the middle part, you get:
x^2 + x -6(2x-1) = 2x-1
This you can reduce to a quadratic equation for x.

2006-11-16 07:17:56 · answer #1 · answered by Anonymous · 1 0

y = x^2 + x - 6 and y = 2x - 1

Substitute linear into quadratic to get:
x^2 + x - 6 = 2x - 1
Rearrange to get:
x^2 - x - 5 = 0
Complete the square:
(x-1/2)^2 - 21/4 = 0
x-1/2 = sqrt(21/4)
x = 1/2 + sqrt(21/4) and x = 1/2 - sqrt(21/4)

2006-11-16 19:32:59 · answer #2 · answered by martina_ie 3 · 0 0

Equate one to the other:

2x-1=x^2+x-6

Make it equalto zero:

x^2-x-5=0

No easy factorisation use quadratic formula:

a=1, b=-1, c=-5

(1 +/- SQROOT((1- (-20))))/2

=(1+/- SQR(21))/2

The answer would be a surd. If you are newto quadratics I would guess you have written the question wrong. If you are at GCSE/A Level standard then the answer would be a surd.

2006-11-16 15:36:30 · answer #3 · answered by Babak m 1 · 1 0

y=x^2 + x - 6y
=> x^2 + x = 7y ---(1)

x^2 + x - 6y = 2x - 1
=> x^2 + x - 6y - 2x + 1 = 0
=> x^2 - x +1 = 6y ---(2)

(1)x6, 6x^2 + 6x = 42y ---(3)
(2)x7, 7x^2 - 7x + 7 = 42y ---(4)
(4)-(3), x^2 - 13x + 7 = 0

x = [13 +- SQRT(169-4(1)(7))] / (2)(1)
x = [13 +- SQRT(141)] / 2
x = 12.4 or 0.563 (to 3 sig fig)

Substitute these values of x into any of the equations to find y.

2006-11-16 19:14:46 · answer #4 · answered by Kemmy 6 · 0 0

y=x^2 + x - 6y=2x - 1
for the moment, forgrt the y= part
x^2+x-6y=2x+1 subtract 2x-1
x^2-x+1-6y=0 since y=2x-1
x^2-x+1-6(2x-1)=0
x^2-13x +7=0
x=(13+/-√(169-28))/2=(13+/-√(141))/2
substitute this in y=2x-1 to find y

2006-11-16 15:22:48 · answer #5 · answered by yupchagee 7 · 0 0

y= x^2 + x - 6 ... (1)
y= 2x - 1 .......... (2)

Equation (1) - equation (2)

0 = x^2 - x - 5

So x = ½(1 ± √41) by the quadratic formula

When x = ½(1 + √41)
y = √41
and when x = ½(1 - √41)
y = - √41

2006-11-16 15:25:54 · answer #6 · answered by Wal C 6 · 2 0

Y = X^2 - x - 6y + 1 = 0
Y + 6Y = X^2 - x + 1
SO Y = X^2 - x + 1 all over 7.

2006-11-16 15:18:31 · answer #7 · answered by Galaxy D 2 · 0 1

y=x^2+x-6......(1)
y=2x-1
......x=(y+1)/2.......(2)
substitute for x into (1)
y=((y+1)/2)^2+(y+1)/2-6
4y=y^2+2y+1+2y+2-24
y^2=21
>>>>>y=+or- sqrt21
from(2),
when y= +sqrt21
x=(sqrt21+(1))/2
when y= -sqrt21
x=(1-sqrt21)/2

1 hope that this helps

2006-11-16 17:44:06 · answer #8 · answered by Anonymous · 0 0

You sure you have the question write? Simultaneous equations should have two distinct equations

2006-11-16 15:19:44 · answer #9 · answered by Jomtien C 4 · 0 0

x^2 -x+1=7y
(x^2-x+1)/7=y
((1/7)+- sqr (1/7)^2 -4*(1/7)*(1/7))7 solve that for your answer

2006-11-16 15:19:58 · answer #10 · answered by dimachevelle 2 · 0 1

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