Cứu vs
2x+5x+12x +x=36
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Câu 1:
\(x^4+5x^3-12x^2+5x+1=x^4+7x^3+x^2-2x^3-14x^2-x+x^2+7x+1\)
\(=\left(x^4+7x^3+x^2\right)-\left(2x^3+14x^2+x\right)+\left(x^2+7x+1\right)\)
\(=x^2\left(x^2+7x+1\right)-2x\left(x^2+7x+1\right)+\left(x^2+7x+1\right)\)
\(=\left(x^2-2x+1\right)\left(x^2+7x+1\right)\)
\(=\left(x-1\right)^2\left(x^2+7x+1\right)\)
Câu 2:
\(\left(x-3\right)\left(x-5\right)\left(x-6\right)\left(x-10\right)-24x^2=x^4-24x^3+203x^2-720x+900-24x^2\)
\(=x^4-24x^3+179x^2-720x+900\)
\(=\left(x^4-7x^3+30x^2\right)-\left(17x^3-119x^2+510x\right)+\left(30x^2-210x+900\right)\)
\(=x^2\left(x^2-7x+30\right)-17x\left(x^2-7x+30\right)+30\left(x^2-7x+30\right)\)
\(=\left(x^2-17x+30\right)\left(x^2-7x+30\right)\)
\(=\left(x^2-2x-15x+30\right)\left(x^2-7x+30\right)\)
\(=\left[x\left(x-2\right)-15\left(x-2\right)\right]\left(x^2-7x+30\right)\)
\(=\left(x-15\right)\left(x-2\right)\left(x^2-7x+30\right)\)
Câu 3:
\(2x^3+11x^2+3x-36=\left(2x^3+14x^2+24x\right)-\left(3x^2+21x+36\right)\)
\(=2x\left(x^2+7x+12\right)-3\left(x^2+7x+12\right)\)
\(=\left(2x-3\right)\left(x^2+7x+12\right)\)
\(=\left(2x-3\right)\left(x^2+3x+4x+12\right)\)
\(=\left(2x-3\right)\left[x\left(x+3\right)+4\left(x+3\right)\right]\)
\(=\left(2x-3\right)\left(x+3\right)\left(x+4\right)\)
a)12 *x= -36
x = -36/12
x = -3
Vậy x= -3
b) -2* |x| = -16
|x| = -16/(-2)
|x| = 8
=>x=8 hoặc x=-8
Vậy x = 8 hoặc x = -8
c) -5x -27 = - 63
-5x = -63 +(-27)
-5x = -90
x = -90/(-5)
x = 18
Vậy x = 18
Thực hiện phép tính:
a. ( 2x - 6 )( 12x2 + 9x + 36 )
b. ( 2x4 + x3 - 3x2 + 5x - 2 ) : ( 5x2 - 5x + 5 )
a)\(\left(5x-1\right)^2-196=0\)
\(\Leftrightarrow\left(5x-1\right)^2=196\)
\(\Leftrightarrow5x-1=14\)
\(\Leftrightarrow x=3\)
b)\(4x^2+\frac{1}{4}=2x\)
\(\Leftrightarrow4x^2+\frac{1}{4}-2x=0\)
\(\Leftrightarrow\left(2x-\frac{1}{2}\right)^2=0\)
\(\Leftrightarrow2x+\frac{1}{2}=0\)
\(\Leftrightarrow x=-\frac{1}{4}\)
c)\(x^2-12x=-36\)
\(\Leftrightarrow x^2-12x+36=0\)
\(\Leftrightarrow\left(x-6\right)^2=0\)
\(\Leftrightarrow x-6=0\)
\(\Leftrightarrow x=6\)
#H
a) (5x - 1)2 - 196 = 0
<=> (5x - 1 - 14)(5x - 1 + 14) = 0
<=> (5x - 15)(5x + 13) = 0
<=> \(\orbr{\begin{cases}5x-15=0\\5x+13=0\end{cases}}\) <=> \(\orbr{\begin{cases}x=3\\x=-\frac{13}{5}\end{cases}}\)
Vậy S = {3; -13/5}
b) Ta có: 4x2 + 1/4 = 2x
<=> 16x2 - 8x + 1 = 0
<=> (4x - 1)2 = 0
<=> 4x- 1 = 0
<=> x = 1/4
Vậy S = {1/4}
c) x2 - 12x = -36
<=> x2 - 12x + 36 = 0
<=> (x - 6)2 0
<=> x - 6 = 0
<=> x = 6
Vậy S = {6}
=> x(2 + 5 + 12 + 1) = 36
=> x.20 = 36
=> x = 1,8
2x + 5x + 12x + x = 36 => x(2 + 5 +12 +1) = 36 => x.20 = 36 => x = 36 : 20 => x=9/5
vậy x= 9/5