Find the equation of conjugate hyperbola whose equations of asymptotes are x + 2y + 3 = 0 and 3x + 4y + 5 = 0 and hyperbola passes through (1, -1).
Combined equation of asymptotes (x+2y+5)(3x+4y+5)=0
3x2+4xy+5x+6xy+8y2+10y+9x+12y+15=0
3x2+8y2+10xy+14x+22y+15=0
only difference between equation of hyperbola and the equation of asymptotes is constant part.
equation of hyperbola is
3x2+8y2+10xy+14x+22y+λ=0 (1)
Since it passes through the point(1,-1)
substituting the x=1 & y=-1 in equation (1)
3×1+8×1+10×(1)(−1)+14×1+22×(−1)+λ=0
3+8−10+14−22y+λ=0
λ=7
equation of hyperpola is
3x2+8y2+10xy+14x+22y+7=0
Constant part of equation of hyperbola,asymptotes and conjugate hyperbola are in AP
we observe that constant part of hyperbola is 7,asymptotes is 15.
then constant part of conjugate hyperpola is 23
Equation of conjugate hyperbola is
3x2+8y2+10xy+14x+22y+23=0