Tìm x biết a) 5x ( x – 3 )^2 + 5 ( x – 4 ) ( x + 4 ) – 5x^3 = -5x ( 6x – 1 ) 23/07/2021 Bởi Charlie Tìm x biết a) 5x ( x – 3 )^2 + 5 ( x – 4 ) ( x + 4 ) – 5x^3 = -5x ( 6x – 1 )
Đáp án: $b)5x(x-3)^2+5(x-4)(x+4)-5x^3=-5x(6x-1)$$⇔5x(x^2-6x+9)+5(x^2-16)-5x^3=-30x^2+5x$$⇔5x^3-30x^2+45x+5x^2-80-5x^3=-30x^2+5x$$⇔-25x^2+45x-80=-30x^2+5x$$⇔-25x^2+45x-80+30x^2-5x=0$$⇔5x^2+40x-80=0$$⇔5(x^2+8x-16)=0$$⇔x^2+8x-16=0$$\text{ $x∈\{4-4\sqrt{2};-4+4\sqrt{2}\}$ }$ @Yết gửi bạn nhé~~ HỌC TỐT~~ #NOCOPY #NOTHINGISIMPOSSIBLE Bình luận
Đáp án: $b)5x(x-3)^2+5(x-4)(x+4)-5x^3=-5x(6x-1)$ $5x(x^2-6x+9)+5(x^2-16)-5x^3=-30x^2+5x$ $5x^3-30x^2+45x+5x^2-80-5x^3=-30x^2+5x$ $-25x^2+45x-80=-30x^2+5x$ $-25x^2+45x-80+30x^2-5x=0$ $5x^2+40x-80=0$ $5(x^2+8x-16)=0$ $x^2+8x-16=0$ $\text{ $x∈\{4-4\sqrt{2};-4+4\sqrt{2}\}$ }$ HỌC TỐT NHA~~ Bình luận
Đáp án:
$b)5x(x-3)^2+5(x-4)(x+4)-5x^3=-5x(6x-1)$
$⇔5x(x^2-6x+9)+5(x^2-16)-5x^3=-30x^2+5x$
$⇔5x^3-30x^2+45x+5x^2-80-5x^3=-30x^2+5x$
$⇔-25x^2+45x-80=-30x^2+5x$
$⇔-25x^2+45x-80+30x^2-5x=0$
$⇔5x^2+40x-80=0$
$⇔5(x^2+8x-16)=0$
$⇔x^2+8x-16=0$
$\text{ $x∈\{4-4\sqrt{2};-4+4\sqrt{2}\}$ }$
@Yết gửi bạn nhé~~
HỌC TỐT~~
#NOCOPY
#NOTHINGISIMPOSSIBLE
Đáp án:
$b)5x(x-3)^2+5(x-4)(x+4)-5x^3=-5x(6x-1)$
$5x(x^2-6x+9)+5(x^2-16)-5x^3=-30x^2+5x$
$5x^3-30x^2+45x+5x^2-80-5x^3=-30x^2+5x$
$-25x^2+45x-80=-30x^2+5x$
$-25x^2+45x-80+30x^2-5x=0$
$5x^2+40x-80=0$
$5(x^2+8x-16)=0$
$x^2+8x-16=0$
$\text{ $x∈\{4-4\sqrt{2};-4+4\sqrt{2}\}$ }$
HỌC TỐT NHA~~