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If 2x² + 2y² - 2x + 2y +1 = 0. Find x+y |
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Answer» Answer: x² + y² - 14x + 2y + 2xy + 17 = 0 4x² + y² - 4XY + 104x + 148y - 124 = 0 Step-by-step explanation: (1) Given Equation is x = y - 1 It can be written as, x - y = -1 ---- (i) -y = -x - 1 y = x + 1 ∴ Slope = 1. ∴ Slope of axis = -1. Equation of axis is y - 1 = -1(x - 2) y - 1 = -x + 2 y - 1 + x - 2 = 0 x + y - 3 = 0 ---- (ii) On solving (i) & (ii), we get x - y = -1 x + y = 3 ------------ 2X = 2 x = 1 Substitute x = 1 in (i), we get x - y = -1 1 - y = -1 y = 2 ∴ The directrix and axis intersects at A(1,2) LET h(s,k) be the focus of parabola. ∴ V(2,1) is the mid-point of AS. ∴ 2 = 1 + h/2 and 1 = 2 + k/2 h = 3, k = 0. ∴ Focus is S(3,0). Let P(x,y) be any point on parabola. PS = PM ⇒√(x - 3)² + (y - 0)² = |x -y + 1/√1 + 1| On Squaring both sides, we get ⇒ (x - 3)² + y² = (x - y + 1)^2/2) ⇒ x² + 9 - 6y + y² = x² + y² + 1 - 2xy - 2y + 2x/2 ⇒ 2x² + 18 - 12y + 2y² = x² + y² + 1 - 2xy - 2y + 2x ⇒ x² + y² - 14x + 2y + 2xy + 17 = 0 -------------------------------------------------------------------------------------------- (2) Let the focus be S(-6,-6) and vertex be A(-2,2) Let z(x,y) be the projection of S on directrix. A is the mid-point of SZ. ⇒ (-2,2) = (-6 + x/2, -6 + y/2) ⇒ x = 2, y = 10. ∴ Z = (2,10) Slope of directrix = -1/(-6 - 2/-6 + 2) = -1/2.. Equation of directrix is y - 10 = -1/2(x - 2) ⇒ 2y - 20 = -x + 2 ⇒ 2y - 20 + x - 2 = 0 ⇒ x + 2y - 22 = 0. Let P(x,y) be any point on the parabola, then SP = PM SP² = PM²{PM is the perpendicular from P to the directrix} ⇒ (x + 6)² + (y + 6)² = (x+ 2y - 22)²/1² + 4 ⇒ x² + 36 + 12x + y² + 36 + 12y = x² + 4xy - 44x + 4y² - 88y + 484/5 ⇒ 5(x² + 36 + 12x + y² + 36 + 12y) = x² + 4xy - 44x + 4y² - 88y + 484 ⇒ 5x² + 60x + 5y² + 60Y + 360 = x² + 4xy - 44x + 4y² - 88y + 484 ⇒ 5x² + 104x - 4yx + y² + 148y - 124 - x² = 0 ⇒ 4x² + y² - 4xy + 104x + 148y - 124 = 0 (or) (2x - y)² + 104x + 148y - 124 = 0 Hope it helps! |
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