The diagram shows the graph of
$x^2 + y^2 = 30.25$ - Edexcel - GCSE Maths - Question 20 - 2021 - Paper 1
Question 20
The diagram shows the graph of
$x^2 + y^2 = 30.25$.
Use the graph to find estimates for the solutions of the simultaneous equations
$x^2 + y^2 = 30.25$
y - 2x =... show full transcript
Worked Solution & Example Answer:The diagram shows the graph of
$x^2 + y^2 = 30.25$ - Edexcel - GCSE Maths - Question 20 - 2021 - Paper 1
Step 1
y - 2x = 1
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Answer
To find the points of intersection between the circle and the line defined by the equation y−2x=1, we can rearrange the equation to express y:
y=2x+1.
Now we substitute this expression into the first equation:
x2+(2x+1)2=30.25
Expanding this:
x2+(4x2+4x+1)=30.25
Combining like terms:
5x2+4x+1−30.25=0
Thus:
5x2+4x−29.25=0
Using the graph, at the intersections, we can estimate the values for x.
From the graph, we can approximate two pairs of (x, y) values for the intersection points:
xextapproximately2.2, then substituting to find y:
y=2(2.2)+1extapproximately5.4.
So, one estimated coordinate is (2.2,5.4).
xextapproximately−4.6, then substituting to find y:
y=2(−4.6)+1extapproximately−8.2.
So, another estimated coordinate is (−4.6,−8.2).