Tìm X : ( x + 4 ) + ( x + 9 ) + ( x + 14 ) + ..... + ( x + 49 ) + ( x + 54 ) = 1430
Tìm x, biết :
a) \(x\cdot\frac{1}{2}+x\cdot\frac{1}{4}+x\cdot\frac{1}{8}=\frac{21}{24}\)
b) (x+4)+(x+9)+(x+14)+...+(x+44)+(x+49)=1430
c) x* 0,25-0,5=1
Chứng minh rằng (9^2n+1994^93)chia heets cho 5
a) \(x\cdot\frac{1}{2}+x\cdot\frac{1}{4}+x\cdot\frac{1}{8}=\frac{21}{24}\)
\(x\cdot\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}\right)=\frac{7}{8}\)
\(x\cdot\frac{7}{8}=\frac{7}{8}\)
\(\Rightarrow x=\frac{7}{8}\div\frac{7}{8}=1\)
b) \(\left(x+4\right)+\left(x+9\right)+\left(x+14\right)+.....+\left(x+44\right)+\left(x+49\right)=1430\)
\(\left(x+x+x+....+x+x\right)+\left(4+9+14+...+44+49\right)=1430\)
\(10x+265=1430\)
\(10x=1430-265\)
\(10x=1165\)
\(\Rightarrow x=\frac{1165}{10}=116,5\)
c) \(x\cdot0,25-0,5=1\)
\(x\cdot0,25=1+0,5\)
\(x\cdot0,25=1,5\)
\(\Rightarrow x=1,5\div0,25=6\)
1,Tính nhanh
a, 568 + 568 x 135 - 568 x 36
b, 17 x 49 + 49 x 37 + 54 x 26 + 54 x 25
c, 14 x 35 x 5 + 10 x 25 x 7 + 20 x 70
a, 568 + 568 x 135 - 568 x 36
= 568 x ( 1 + 135 - 36)
= 568 x 100
56 800
b, 17 x 49 + 49 x 37 + 54 x 26 + 54 x 25
= 49 x ( 17 + 37) + 54 x ( 26 + 25 )
= 49 x 54 + 54 x 51
= 54 x ( 49 + 51)
= 54 x 100
= 5 400
c, 14 x 35 x 5 + 10 x 25 x 7 + 20 x 70
= ( 2 x 35) x ( 7 x 5) + ( 10 x 7) x 25 + 20 x 70
= 70 x 35 + 70 x 25 + 20 x 70
= 70 x ( 35 + 25 + 20)
= 70 x 80
= 5 600
a) 568 + 568 x 135 - 568 x 36
= 568 x ( 1+1+135-1-36 )
=568 x 100
=5680
b) 17 x 49 + 49 x 37 + 54 x 26 + 54 x 25
= 49 x ( 17 + 37 ) + 54 x ( 26 + 25 )
= 49 x 54 + 54 x 51
= 54 x ( 49 + 51 )
= 54 x 100
= 5400
c) 14 x 35 x 5 + 10 x 25 x 7 + 20 x 70
= 70 x 35 + 10 x 25 x 7+ 20 x 70
= 70 x 35 + 250 x 7 + 20 x 70
= 70 x 35 + 70 x 25 + 20 x 70
= 70 x (35+25+20)
= 70 x 80
= 5600
Giúp tớ với tìm x : x- -18/54=7/9(âm 18) -14/42-x=-4/7
a: \(x-\dfrac{-18}{54}=\dfrac{7}{9}\cdot\left(-18\right)\)
=>x+1/3=7/9*(-18)=-7
=>x=-7-1/3=-22/3
b: -x-14/42=-4/7
=>x+1/3=4/7
=>x=4/7-1/3=12/21-7/21=5/21
Tìm số tự nhiên x biết 54 - 49 / (x+4) = 49 ?
54-49/(x+4)=49
54-49=49.(x+4)
5=49.(x+4)
x+4=5/49
x=-191/49
49/(x+4) = 54-49=5
5x+20=49
5x =29
x =29/5
( 4 + x ) + ( 9 + x) + ( 14 + x) + ... + ( 54 + x) = 354
( 4 + x ) + ( 9 + x ) + ( 14 + x ) +...+ ( 54 + x ) =354
4+x+9+x+14+x+...+54+x=354
(4+9+14+...+54)+ 11x =354
319 + 11x =354
11x=35
x=35/11
( 4 + x ) + ( 9 + x) + ( 14 + x) + ... + ( 54 + x) = 354
(4+96)+(9+49)+(14+136)+(54+0)
(4 + x) + (9 + x) + ( 14 + x) +...+ (54 + x) =354
4 + x + 9 + x + 14 + x +...+ 54 + x =354
11x + {[( 54 + 4) x 11] : 2} =354
11x+319 =354
11x =354 - 319
11x =35
x =35 : 11
x =35/11
Tìm x,biết:
A) 8 + ( x - 9)= 125 - 64
B) 5×(x+7) -10 = 8×5
C) 7 × 7 - 7( 13 - 2× x) = 14
D) 320 : (x - 1) = ( 125 - 5 ×5 ) : 4 + 15
E) 240 : ( x -5 ) = 4 × 5 ×5 - 60 : 3
F) 49 × x - 14 × x = 49 × 10 - 70
a. 8 + (x - 9) = 125 - 64
8 + (x - 9) = 61
x - 9 = 53
x = 62
b. 5 x (X + 7) - 10 = 8 x 5
5 x (X + 7) - 10 = 40
5 x (X + 7) = 50
X + 7 = 10
X = 3
Tim x thuoc N biet:
a, (225-x) -81=54
b, 7.(x-14)+35= 25+279:9
c, 7x : 49= 727
a. => 225-x=135
=> x=225-135
Vậy x=90.
b. => 7.(x-14)+35=25+31
=> 7.(x-14)=25+31-35
=> 7.(x-14)=21
=> x-14=3
=> x=3+14
Vậy x=17
c. => 7x:72=727
=> 7x-2=727
=> x-2=27
=> x=27+2
Vậy x=29.
Giải các phương trình sau:
9) x-49/ 50 + x-50/ 49 = 49/ x-50 + 50/ x-49
8) 99-x/101 + 97-x/103 + 95-x/105 + 93-x/107 = 4
10) x+14/86 + x+15/85 + x+16/84 + x+17/83 + x+116/4 = 0
10) \(\frac{x+14}{86}+\frac{x+15}{85}+\frac{x+16}{84}+\frac{x+17}{83}+\frac{x+116}{4}=0\)
\(\Leftrightarrow\)\(\frac{x+14}{86}+1+\frac{x+15}{85}+1+\frac{x+16}{84}+1+\frac{x+17}{83}+1+\frac{x+116}{4}-4=0\)
\(\Leftrightarrow\)\(\frac{x+100}{86}+\frac{x+100}{85}+\frac{x+100}{84}+\frac{x+100}{83}+\frac{x+100}{4}=0\)
\(\Leftrightarrow\)\(\left(x+100\right)\left(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\right)=0\)
\(\Leftrightarrow\)\(x+100=0\) (vì 1/86 + 1/85 + 1/84 + 1/83 + 1/4 \(\ne\)0)
\(\Leftrightarrow\)\(x=-100\)
Vậy....
x/7+9/49=3/14 tìm x
\(\frac{x}{7}+\frac{9}{49}=\frac{3}{14}\)
\(\Rightarrow\frac{x}{7}=\frac{3}{14}-\frac{9}{49}=\frac{3}{98}\)
\(\Rightarrow x=3.7:98=\frac{3}{14}\)
Vậy \(x=\frac{3}{14}\)