tim x : b, (2x-1)+(x+3)mũ 2 – 5(x-7 ) . ( x+7 ) = 0 anh chi giup e nhanh voi ak em dg can gap :’) 15/08/2021 Bởi Autumn tim x : b, (2x-1)+(x+3)mũ 2 – 5(x-7 ) . ( x+7 ) = 0 anh chi giup e nhanh voi ak em dg can gap :’)
$(2x -1) + (x+3)^2 – 5(x – 7)(x+7) = 0$ $\Leftrightarrow 2x – 1 + x^2 + 6x + 9 – 5(x^2 – 49) = 0$ $\Leftrightarrow -4x^2 + 8x +253 = 0$ $\Leftrightarrow \left[\begin{array}{l} x =\dfrac{2 – \sqrt{257}}{2}\\x = \dfrac{2 + \sqrt{257}}{2}\end{array}\right.$ Nếu đề là: $(2x -1)^2 + (x+3)^2 – 5(x – 7)(x+7) = 0$ $\Leftrightarrow 4x^2 – 4x + 1 + x^2 + 6x + 9 – 5(x^2 – 49) = 0$ $\Leftrightarrow 2x + 255 = 0$ $\Leftrightarrow x = -\dfrac{255}{2}$ Bình luận
$(2x -1) + (x+3)^2 – 5(x – 7)(x+7) = 0$
$\Leftrightarrow 2x – 1 + x^2 + 6x + 9 – 5(x^2 – 49) = 0$
$\Leftrightarrow -4x^2 + 8x +253 = 0$
$\Leftrightarrow \left[\begin{array}{l} x =\dfrac{2 – \sqrt{257}}{2}\\x = \dfrac{2 + \sqrt{257}}{2}\end{array}\right.$
Nếu đề là: $(2x -1)^2 + (x+3)^2 – 5(x – 7)(x+7) = 0$
$\Leftrightarrow 4x^2 – 4x + 1 + x^2 + 6x + 9 – 5(x^2 – 49) = 0$
$\Leftrightarrow 2x + 255 = 0$
$\Leftrightarrow x = -\dfrac{255}{2}$