2) (x + 40) x15 = 5 ^ 2 x 3^2x4
tìm a
a, 25 +(15 -a ) =30
b, 2 . ( a-5 ) =1,7
c, [61 + ( 53 -9 )] x 17 = 1785
d, ( x+7 ) : 14 -40 = ( 32 x15 ) :2
a)3x5^2-27:3^2-5^2x4-18:3^2
b)2x -1 là bội của x-3
c)205-[ 1200-(4^2 - 2x3)^3] :40
a) \(3.5^2-27:3^2-5^2.4-18:3^2\)
\(=3.\left(5^2-5^2\right).27:\left(3^2-3^2\right)\)
\(=15.0.27.0\)
\(=0.0=0\)
b)
2x-1 là bội của x+3
=> 2x-1 chia hết cho x+3
hay [2(x+3)-7] chia hết ho x+ 3
=> 7 chia hết cho x+ 3
x+3 εεƯ(7)={1,-1,7,-7}
x+3=1 x+3=-1 x+3=7 x+3= -7
x = 1-3 x = -1-3 x = 7-3 x = -7-3
x = -2 x = -4 x =4 x = -10
Vậy x= -2, x=-4,x= 4, x= -10
c) \(205-\left[1200-\left(4^2-2.3\right)^3\right]:40\)
\(=205-\left[1200-16-6^3\right]:40\)
\(=205-\left[1200-10^3:40\right]\)
\(=205-1200-1000:40\)
\(=205-200:40\)
\(=205-5\)
\(=200\)
tìm X :
a, X+X : 3 x15 = 324/4 + 102/6
b,100-X +5x2 /2 -5 = 0
Tính các tổng sau
2/11x13 + 2/13 x15 + 2/15 x17 + ............ + 2/95x97 +2/97x9 = ?
1 x 2 + 2 x 3 + 3 x 4 + 4 x 5 .......... + 99 x 100 = ?
Đặt A = 1.2 + 2.3 + 3.4 +.......... + 99.100
=> 3A = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ..... + 99.100.(101 - 98)
=> 3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + ....... + 99.100.101 - 98.99.100
=> 3A = (1.2.3 + 2.3.4 + 3.4.5 + ....... + 99.100.101) - (1.2.3 + 2.3.4 + ......... + 98.99.100)
=> 3A = 99.100.101
=> A = 99.100.101 : 3 = 999900
2/11x13+2/13x15+2/15x17+....+2/95x97+2/97x99
=1/11-1/13+1/13-1/15+1/15-1/17+....+1/95-1/97+1/97-1/99
=1/11-1/99
=9/99-1/99
=8/99
đúng nhé bạn
Đặt A = 1.2 + 2.3 + 3.4 +.......... + 99.100
=> 3A = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ..... + 99.100.(101 - 98)
=> 3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + ....... + 99.100.101 - 98.99.100
=> 3A = (1.2.3 + 2.3.4 + 3.4.5 + ....... + 99.100.101) - (1.2.3 + 2.3.4 + ......... + 98.99.100)
=> 3A = 99.100.101
=> A = 99.100.101 : 3 = 999900
tính
a)(-12)+(-9)
b)3^2 x 24 +3^2 x76
9^5 -3^2x3
tìm x
a)x-12=-28
b)20+8x(x+3)=5^2x4
)9^5 :9^3-3^2x3
Bài 1:
a: =-21
b: =9x100=900
tính giá trị đa thức M: M=x^3+2x^2y-5x^2+2xy+4y-8y+x15 với x+2y=5
b3 tìm x bt
a, 3/2x4/5-x=2/3
3/2 x 4/5 - x = 2/3
6/5 - x = 2/3
x = 6/5 - 2/3
x = 8/15
=> x = 8/15
Bài làm
\(\frac{3}{2}x\frac{4}{5}-X=\frac{2}{3}\)
\(\frac{6}{5}-X=\frac{2}{3}\)
\(X=\frac{6}{5}-\frac{2}{3}\)
\(X=\frac{18}{15}-\frac{10}{15}\)
\(X=\frac{8}{15}\)
# Chúc bạn học tốt #
1. (x3 – 3x2 + x – 3) : (x – 3) 2. (2x4 – 5x2 + x3 – 3 – 3x) : (x2 – 3) 3. (x – y – z)5 : (x – y – z)3 4. (x2 + 2x + x2 – 4) : (x + 2) 5. (2x3 + 5x2 – 2x + 3) : (2x2 – x + 1) 6. (2x3 – 5x2 + 6x – 15) : (2x – 5)
1: \(=x^2+1\)
3: \(=\left(x-y-z\right)^2\)
Giải giúp mình với:
Tìm X
15:(x+2)=3
\(15:\left(x+2\right)=3\)
\(\Rightarrow x+2=15:3=5\)
\(\Rightarrow x=5-2=3\)
15:(x+2)=3
nên x+2=5
hay x=3