Bài 2 : Tìm X
A. ( X + 1 ) + ( X+ 2 ) + ( X + 3 ) + ....... + ( X + 50 ) = 2275
B. x04 + 40x = 101 x 11
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x04+40x = 100xX +4 + 400 +X = 101xX +404 = 101xX +101x4 =101x (X+4) = 101x11 => X+4 =11 => X =7
Bài 1:
\(101\cdot125+101\cdot25-101\cdot50\)
\(=101\cdot\left(125+25-50\right)\)
\(=101\cdot100\)
\(=10100\)
Bài 2:
\(76\cdot115+56\cdot24+59\cdot24\)
\(=76\cdot115+24\cdot\left(56+59\right)\)
\(=76\cdot115+24\cdot115\)
\(=115\cdot\left(76+24\right)\)
\(=115\cdot100\)
\(=11500\)
A = \(\dfrac{3^{100}.\left(-2\right)+3^{101}}{\left(-3\right)^{101}-3^{100}}\)
A = \(\dfrac{3^{100}.\left(-2\right)+3^{100}.3}{\left(-3\right)^{100}.\left(-3\right)-3^{100}}\)
A = \(\dfrac{3^{100}.\left(-2+3\right)}{3^{100}.\left(-3\right)-3^{100}}\)
A = \(\dfrac{3^{100}.1}{3^{100}.\left(-3-1\right)}\)
A = \(\dfrac{3^{100}}{3^{100}}\) . \(\dfrac{1}{-4}\)
A = - \(\dfrac{1}{4}\)
\(B1,a,A=x^2-6x+11\)
\(=\left(x^2-6x+9\right)+2\)
\(=\left(x-3\right)^2+2\ge2\)
Dấu "=" <=> x=3
Vậy ..........
\(b,B=x^2-20x+101\)
\(=\left(x^2-20x+100\right)+1\)
\(=\left(x-10\right)^2+1\ge1\)
Dấu "=" <=> x = 10
Vậy .
\(2,a,A=4x-x^2+3\)
\(=7-\left(x^2-4x+4\right)\)'
\(=7-\left(x-2\right)^2\le7\)
Dấu ''='' <=> x = 2
Vậy .
\(b,B=-x^2+6x-11\)
\(=-2-\left(x^2-6x+9\right)\)
\(=-2-\left(x-3\right)^2\le-2\)
Dấu ""=" <=> x = 3
Vậy..
Bài 1: Tính nhanh
A, 13 x 126 + 37 x 126 - 49 x 126
= 126 x ( 13 + 49 - 49 )
= 126 x 1
= 126
B, ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 102 - 101 x 101 - 50 - 51 )
= ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x ( 102 - 101 - 1))
= ( 1 + 2 + 4 + 8+.....+ 512 ) x ( 101 x 0)
= ( 1 + 2 + 4 + 8+.....+ 512 ) x 0
= 0
Phần 2: 1998 x 1996 + 1997 x 11 + 1985 / 1997 x 1996 - 1995 x 1996
=1998 x 1996+ 1997 x 11 +1985/1997x1996 - 1995 x 1996
=1998x11+1985/1995x1996
=23963/3982020
không chắc lắm đâu,câu này bạn hỏi rồi mà
a/ (x+1)+(x+2)+(x+3)+....+(x+50)=2275
<=> (x+x+...+x)+(1+2+3+...+50)=2275
<=> \(50x+\frac{50\left(50+1\right)}{2}=2275\)
<=> 50.x+1275=2275
<=> 50x=1000
=> x=1000:50 => x=20
b/ x04+40x=101x11
<=> 100x+4+400+x=1111
<=> 101x=707
=> x=707:101 => x=7
a, ( x + 1 ) + ( x + 2 ) + ( x + 3 ) + ... + ( x + 50 ) = 2275
x x 50 + ( 50 + 1 ) x ( 50 : 2 ) = 2257
x x 50 + 51 x 25 = 2257
x x 50 + 1275 = 2257
x x 50 = 2257 - 1275
x x 50 = 982
x = 982 : 50
x = 19,64