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Guys, I really want to get a A on my maths exam. I am currently in year 10. What do you guys think is the best revision/method to getting that A? I am currently going through past papers

 

Solve algebraically the simultaneous equations
x2 + y2 = 25
y – 3x = 13

 Feb 17, 2019
 #1
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Alright Lewis, we can do this.

We can use the equation y - 3x = 13 and turn it into y = 3x + 13.

We subsitute it for y in the top equation.

This gives us x2 + (3x+13)(3x+13)=25

x2+9x2+39x+39x+169=25

10x2+78x+169=25

10x2+78x+144=0

5x2+39x+72=0

Using the quadratic formula we get 

x=-3, -24/5

We can then test these numbers(They work).

After substituting the x back in, y values are 4, -7/5

 

YEETUS

(My first problem :))

 Feb 17, 2019
edited by Badada  Feb 17, 2019

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