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5 Answers
- ?Lv 78 years agoFavorite Answer
1-2x=x^2-3x-5
x^2-x-6=0
(x-3)(x+2)=0
x=3 or x=-2
apply this to the 1st equation
when x=3 y=1-2(3)=-5
when x=-2 y=1-2(-2)=5
answer x=3,y=-5 or x=-2,y=5
- 8 years ago
You have to substitute the linear equation into the quadratic.
Since y is common to both equations, you can write this:
1-2x=x^2-3x-5
and from this:
x^2-x-6=0
Then solve this as you would any other quadratic.
(x-3)(x+2)=0
Then:
x-3=0
x=3
and x+2=0
x=-2
Substitute these values into the linear equation:
y=1-2x
y=1-2(3)
y=-5
and y=1-2(-2)
y=5
so you get the two solutions, which should be written as pairs:
x=3 and x=-2
y=-5 y=5
Source(s): AS level maths and further maths student - 8 years ago
from the given 2 equations we have
x^2 -3x-5=1 - 2x
=>x^2-x-6=0
=>x^2-3x+2x-6=0
=>(x-3)(x+2)=0
therefore either x=2 or x=3
when x= - 2 then from first equation we have y=1 - 2*(-2)= 5
and when x=3 then from first equation we have y=1 - 2*3= - 5
- YashLv 48 years ago
y = 1 - 2x --------1)
y = x^2 - 3x - 5 ----------2)
Substitute eqn 1) in eqn 2)
1 - 2x = x^2 - 3x - 5
x^2 - 3x + 2x - 5 - 1 = 0
x^2 - x - 6 = 0
x^2 - 3x + 2x - 6 = 0
x(x - 3)+2(x - 6) = 0
(x - 3) (x + 2) = 0
x = 3 or x = -2
Substitute these two values in eqn 1)
When x = 3
y = 1 - 2x = 1 - 2(3) = 1 - 6 = -5
When x = -2
y = 1 - 2x = 1 - 2(-2) = 1 + 4 = 5
(x,y) = (3,-5) or (x,y) = (-2,5) -----------Answer
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- daSVgrouchLv 78 years ago
as requested, first step only !
y = y which is -
x^2 - 3x - 5 = 1 - 2x
then combine like terms and solve or factor the quadratic