x^10-11x^9+11x^8-11x^7+...-11x^3+11x^2-11x+2 với x=10, bạn nào biết làm chỉ hộ mình vs
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Thay 11= 10+1 ta có
x10-(10+1)x9+(10+1)x8-(10+1)x7+(10+1)x6-(10+1)x5+(10+1)x4-(10+1)x3+(10+1)x2-(10+1)x+2
= x10-(x+1)x9+(x+1)x8-(x+1)x7+(x+1)x6-(x+1)x5+(x+1)x4-(x+1)x3+(x+1)x2-(x+1)x+2
= x10-x10-x9+x9+x8-x8-x7+x7+x6-x6-x5+x5+x4-x4-x3+x3+x2-x2-x+2
= -x+2
Thay x=10 vào bt
= -10+2
= -8
thay 11=x+1 ta có:
f(x)= \(x^{10}\)-11\(x^9\)+11\(x^8\)-11\(x^7\)+....+11\(x^2\)-11x+100
=\(x^{10}\)-(x+1)\(x^9\)+(x+1)\(x^8\)-(x+1)\(x^7\)+...+(x+1)\(x^2\)-(x+1)x+100
=\(x^{10}\)-\(x^{10}\)-\(x^9\)+\(x^9\)+\(x^8\)-\(x^8\)-\(x^7\)+......+\(x^3\)+\(x^2\)-\(x^2\)-x+100
=-x+100
=> f(10)=-10+100=90
Thay 11 = x + 1 ta có:
f(x) = \(x^{10}-11x^9+11x^8-11x^7+...+11x^2-11x+100\)
\(=x^{10}-\left(x+1\right)x^9+\left(x+1\right)x^8-\left(x+1\right)x^7+...+\left(x+1\right)x^2-\left(x+1\right)x^2-\left(x+1\right)x+100\)
= \(x^{10}-x^{10}-x^9+x^9+x^8-x^8-x^7+...+x^3+x^2-x^2-x+100\)
= -x+100
=>f(10)= - 10 + 100 = 90
1.
$-7(5-x)-2(x-10)=15$
$-35+7x-2x+20=15$
$5x-15=15$
$5x=30$
$x=30:5=6$
2.
$3(x-4)-(8-x)=12$
$3x-12-8+x=12$
$4x-20=12$
$4x=12+20=32$
$x=32:4=8$
7(x-3)-5(3-x)=11x-5
<=>7(x-3)+5(x-3)-11x+5=0
<=>12(x-3)-11x+5=0
<=>12x-36-11x+5=0
<=>x-31=0
<=>x=31
a, => 7x-63-30+5x=11x-6
=> 12x-93=11x-6
=> 12x=11x-6+93 = 11x+87
=> 12x-11x=87
=> x=87
b, => 7x-21-15+5x=11x-5
=> 12x-36=11x-5
=> 12x=11x-5+36 = 11x+31
=> 12x-11x=31
=> x=31
Tk mk nha