Solve algebraically the simultaneous equations x^2 + y^2 = 25, y – 3x = 13
Rearrange y - 3x = 13 to y = 13 + 3xSquare y to give y^2 = 169 +78x +9x^2Sub into first equation to give x^2 + 169 + 78x +9x^2 = 25Simplify to give 10x^2 + 78x + 144 = 0 Apply quadratic formula to solve for x, first x = -3 and second x = -24/5Sub back in to give y values, first y = 4 and second y = -7/5Sub back in to check - Answers are correct.
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