Question

Решите систему x2+y2=40 y-3x=0

Answer 1

у=3х х*2+(3х)*2=40 х*2+9х*2=40 10х*2=40 х*2=4 х=+2 х=-2

Answer 2

Y = 3X    Y^2 = 9X^2 
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X^2 + 9X^2 = 40 
10X^2 = 40 
X^2 = 4
X1 = + 2 
X2 = - 2 
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Y1 = + 6 
Y2 = ( - 6) 
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ответ ( - 2 ; - 6) U (  2 ; 6 )