tìm x:
a. (x-1) (x2+x+1)-x (x+2) (x-2)=5
b. (x-1)3-(x+3) (x2-3x+9)+3 (x2-4)=2
Mình cần câu trả lời nhanh nhất có thể. thanks mọi người
Rút gọn các biểu thưc sau:
c.(x -1)3 – (x - 1)(x2 +x+1)
d.(x -3)3 – (x - 3)(x2 +3x+9) + 6(x+1)2
Mình cần gấp!!!!!
c) \(\left(x-1\right)^3-\left(x-1\right)\left(x^2+x+1\right)\)
\(=\left(x-1\right)^3-\left(x-1\right)\left(x^2+x.1+1^2\right)\)
\(=\left(x-1\right)^3-\left(x-1\right)^3\)
\(=0\)
d) \(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x+1\right)^2\)
\(=\left(x-3\right)^3-\left(x-3\right)\left(x^2+x.3+3^2\right)+6\left(x+1\right)^2\)
\(=\left(x-3\right)^3-\left(x-3\right)^3+6\left(x+1\right)^2\)
\(=0+6\left(x+1\right)^2\)
\(=6\left(x+1\right)^2\)
c. (x - 1)3 - (x - 1)(x2 + x + 1)
= (x - 1)3 - (x3 - 1)
= x3 - 2x2 + 2x - 1 - x3 + 1
= x3 - x3 - 2x2 + 2x - 1 + 1
= -2x2 + 2x
d. (x - 3)3 - (x - 3)(x2 + 3x + 9) + 6(x + 1)2
= x3 - 6x2 + 18x - 27 - (x3 - 27) + 6(x2 + 2x + 1)
= x3 - 6x2 + 18x - 27 - x3 + 27 + 6x2 + 12x + 6
= x3 - x3 - 6x2 + 6x2 + 18x + 12x - 27 + 27 + 6
= 30x + 6
tìm x:
a)3(2x-3)+2(2-x)=-3
b)2x(x2-2)+x2(1-2x)-x2=-12
c)3x(2x+3)-(2x+5)(3x-2)=8
d)4x(x - 1) - 3(x2-5)-x2=(x-3)-(x+4)
e)2(3x-1)(2x+5)-6(2x-1)(x+2)=-6
a: Ta có: \(3\left(2x-3\right)+2\left(2-x\right)=-3\)
\(\Leftrightarrow6x-9+4-2x=-3\)
\(\Leftrightarrow4x=2\)
hay \(x=\dfrac{1}{2}\)
Câu III (2,0 điểm) Tìm x, biết:
a) x(x – 1) – x2 + 2x = 5
b) 2x2 – 2x = (x – 1)2
c) (x + 3)(x2 – 3x + 9) – x(x – 2)2 = 19
a) Ta có: \(x\left(x-1\right)-x^2+2x=5\)
\(\Leftrightarrow x^2-x-x^2+2x=5\)
hay x=5
b) Ta có: \(2x^2-2x=\left(x-1\right)^2\)
\(\Leftrightarrow2x\left(x-1\right)-\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)\left(2x-x+1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-1\end{matrix}\right.\)
c) Ta có: \(\left(x+3\right)\cdot\left(x^2-3x+9\right)-x\left(x-2\right)^2=19\)
\(\Leftrightarrow x^3+27-x\left(x^2-4x+4\right)-19=0\)
\(\Leftrightarrow x^3+8-x^3+4x^2-4x=0\)
\(\Leftrightarrow4x^2-4x+8=0\)(Vô lý)
Tìm x:
a)2x3-18x=0
b)(3x-2).(2x+1)-6x.(x+2)=11
c)(x-1)3-(x+2).(x2-2x+4)=3.(1-x2)
a: Ta có: \(2x^3-18x=0\)
\(\Leftrightarrow2x\left(x-3\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\\x=-3\end{matrix}\right.\)
b: Ta có: \(\left(3x-2\right)\left(2x+1\right)-6x\left(x+2\right)=11\)
\(\Leftrightarrow6x^2+3x-4x-2-6x^2-12x=11\)
\(\Leftrightarrow-13x=13\)
hay x=-1
c: Ta có: \(\left(x-1\right)^3-\left(x+2\right)\left(x^2-2x+4\right)=3\left(1-x^2\right)\)
\(\Leftrightarrow x^3-3x^2+3x-1-x^3-8=3-3x^2\)
\(\Leftrightarrow3x=12\)
hay x=4
a) 2x3-18x=0
⇔ 2x(x2-9)=0
⇔ 2x(x-3)(x+3)=0
⇔ \(\left\{{}\begin{matrix}x=0\\x=3\\x=-3\end{matrix}\right.\)
b)(3x-1)(2x+1)-6x(x+2)=11
⇔ 6x2+x-1-6x2-12x=11
⇔ -11x=12
\(\Leftrightarrow x=-\dfrac{12}{11}\)
c) (x-1)3-(x+2).(x2-2x+4)=3.(1-x2)
⇔ x3-3x2+3x-1-x3-8-3+3x2=0
⇔ 3x=12
⇔ x=4
c. (x - 1)3 - (x + 2)(x2 - 2x + 4) = 3(1 - x2)
<=> (x3 - 3x2 + 3x - 1) - (x3 - 2x2 + 4x + 2x2 - 4x + 8) = 3 - 3x2
<=> x3 - 3x2 + 3x - 1 - x3 + 2x2 - 4x - 2x2 + 4x - 8 = 3 - 3x2
<=> x3 - x3 - 3x2 + 2x2 - 2x2 + 3x2 + 3x - 4x + 4x = 3 + 1 + 8
<=> 3x = 12
<=> x = 4
Mọi người làm nhanh hộ e với ạ, T7 e nộp r
Bài 1.
Tính:
a. x2(x–2x3) b. (x2+ 1)(5–x) c. (x–2)(x2+ 3x–4) d. (x–2)(x–x2+ 4)
e. (x2–1)(x2+ 2x) f. (2x–1)(3x + 2)(3–x) g. (x + 3)(x2+ 3x–5)
h (xy–2).(x3–2x–6) i. (5x3–x2+ 2x–3).(4x2–x + 2)
Bài 2.
Tính:
a. (x–2y)2 b. (2x2+3)2 c. (x–2)(x2+ 2x + 4) d. (2x–1)2
Bài 3: Rút gọn biểu thức
a.(6x + 1)2+ (6x–1)2–2(1 + 6x)(6x–1)
b. x(2x2–3)–x2(5x + 1) + x2.
c. 3x(x–2)–5x(1–x)–8(x2–3)
Bài 4: Tìm x, biết
a. (x–2)2–(x–3)(x + 3) = 6.
b. 4(x–3)2–(2x–1)(2x + 1) = 10
c. (x–4)2–(x–2)(x + 2) = 6.
d. 9 (x + 1)2–(3x–2)(3x + 2) = 10
Bài 5:Phân tích các đa thức sau thành nhân tử
a. 1–2y + y2
b. (x + 1)2–25
c. 1–4x2
d. 8–27x3
e. 27 + 27x + 9x2+ x3
f. 8x3–12x2y +6xy2–y3
g. x3+ 8y3
Bài 6:Phân tích các đa thức sau thành nhân tử
a. 3x2–6x + 9x2
b. 10x(x–y)–6y(y–x)
c. 3x2+ 5y–3xy–5x
d. 3y2–3z2+ 3x2+ 6xy
e. 16x3+ 54y3
f. x2–25–2xy + y2
g. x5–3x4+ 3x3–x2
.
Bài 7: Phân tích đa thức thành nhân tử
a. 5x2–10xy + 5y2–20z2
b. 16x–5x2–3
c. x2–5x + 5y–y2
d. 3x2–6xy + 3y2–12z2
e. x2+ 4x + 3
f. (x2+ 1)2–4x2
g. x2–4x–5
Bài 5:
a. 1 - 2y + y2
= (1 - y)2
b. (x + 1)2 - 25
= (x + 1)2 - 52
= (x + 1 - 5)(x + 1 + 5)
= (x - 4)(x + 6)
c. 1 - 4x2
= 12 - (2x)2
= (1 - 2x)(1 + 2x)
d. 8 - 27x3
= 23 - (3x)3
= (2 - 3x)(4 + 6x + 9x2)
e. (đề hơi khó hiểu ''x3'' !?)
g. x3 + 8y3
= (x + 2y)(x2 - 2xy + y2)
Tìm X:
a) (x + 3)2 – x2 + 15 = 1
b) (5 – x)2 + 6x – x2 = –7
c) (1 + x)(1 – x) – (x – 4)2 = –15
giúp mik với mik cần gấp!!
a)(x+3)2-x2+15=2x+6-2x+15=1
=21=1
Bạn chép sai đầu bài à
Tìm x:
a,2/5 + x= 13/15 - 1/3
b,x- 2/9= 2/3 x2
Cho mình câu trả lời nhanh nhất nhé!
a) \(\frac{2}{5}\)+ X = \(\frac{13}{15}\) - \(\frac{1}{3}\)
\(\frac{2}{5}+X=\frac{8}{15}\)
\(X=\frac{8}{15}-\frac{2}{5}\)
\(X=\frac{2}{15}\)
a) 2/5 + x = 13/15 - 1/3
2/5 + x = 8/15
x = 8/15 - 2/5
x = 2/15
b) x - 2/9 = 2/3 x 2
x - 2/9 = 4/3
x = 4/3 + 2/9
x = 14/9
a) 2/5 + x =8/15 b) x- 2/9 = 4/3
x =8/15 - 2/5 x =4/3+2/9
x = 2/15 x =14/9
Tìm x:
a)x.(x-1)-(x-2)2=2
b)x2-9=(x-3).(6-x)
c)x2-x-6=0
Tìm x:
a)x.(x-1)-(x-2)2=2
b)x2-9=(x-3).(6-x)
c)x2-x-6=0
\(a,\Leftrightarrow x^2-x-x^2+4x-4=2\\ \Leftrightarrow3x=6\Leftrightarrow x=2\\ b,\Leftrightarrow\left(x-3\right)\left(x+3\right)-\left(x-3\right)\left(6-x\right)=0\\ \Leftrightarrow\left(x-3\right)\left(x+3-6+x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{3}{2}\end{matrix}\right.\\ c,\Leftrightarrow x^2+2x-3x-6=0\\ \Leftrightarrow\left(x+2\right)\left(x-3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)