{x+1997 } + 2003 = 5432

x+1997=5432-2003

x+1997=3429

x=3429-1997

x=1432

329-{129+x } = 14 *7

329-(129+x)=98

129+x=329-98

129+x=231

x=231-129

x=102

\(a.\)

\(\left(x^2-25\right):\dfrac{2x+10}{3x-7}\)

\(=\left(x-5\right)\left(x+5\right).\dfrac{3x-7}{2\left(x+5\right)}\)

\(=\dfrac{\left(x-5\right)\left(x+5\right)\left(3x-7\right)}{2\left(x+5\right)}\)

\(=\dfrac{\left(x-5\right)\left(3x-7\right)}{2}\)

\(b.\)

\(\dfrac{x^2+x}{5x^2-10x+5}:\dfrac{3x+3}{5x-5}\)

\(=\dfrac{x\left(x+1\right)}{5\left(x^2-2x+1\right)}.\dfrac{5\left(x-1\right)}{3\left(x+3\right)}\)

\(=\dfrac{x\left(x+1\right)}{5\left(x-1\right)^2}.\dfrac{5\left(x-1\right)}{3\left(x+1\right)}\)

\(=\dfrac{x\left(x+1\right).5\left(x-1\right)}{5\left(x-1\right)^2.3\left(x+1\right)}\)

\(=\dfrac{x}{3\left(x-1\right)}\)

\(\dfrac{x^2+x}{5x^2-10x+5}:\dfrac{3x+3}{5x-5}=\dfrac{5x\left(x+1\right)\left(x-1\right)}{15\left(x-1\right)^2\left(x+1\right)}=\dfrac{x}{3\left(x-1\right)}\)\(\left(x^2-25\right):\dfrac{2x+10}{3x-7}=\dfrac{\left(x-5\right)\left(x+5\right)\left(3x-7\right)}{2\left(x+5\right)}=\dfrac{\left(x-5\right)\left(3x-7\right)}{2}\)

aigiup mijn vs kho qua!!

Số số hạng của tổng trên là: (100 - 1) : 1 + 1 = 100(số)

Tổng trên là: (100+1)x 100 : 2 = 5050

a ) \(\left(3x^2-4x+5\right)\left(2x^2-4\right)-2x\left(3x^3-4x^2+8\right)\)

\(=\left(3x^2-4x+5\right).2x^2-4\left(3x^2-4x+5\right)-6x^4+8x^3-16x\)

\(=6x^4-8x^3+10x^2-12x^2+16x-20-6x^4+8x^3-16x\)

\(=\left(6x^4-6x^4\right)+\left(8x^3-8x^3\right)-\left(12x^2-10x^2\right)+\left(16x-16x\right)-20\)

\(=-2x^2-20\)

b ) \(\left(1-3x+x^2\right)\left(2-4x\right)+2x\left(2x^2+5\right)\)

\(=2\left(1-3x+x^2\right)-4x\left(1-3x+x^2\right)+4x^3+10x\)

\(=2-6x+2x^2-4x+12x^2-4x^3+4x^3+10x\)

\(=\left(4x^3-4x^3\right)+\left(12x^2+2x^2\right)+\left(10x-6x-4x\right)+2\)

\(=14x^2+2\)

a/đkxđ: \(x\ne0;x\ne3\)

\(\frac{x}{x-3}+\frac{9-6x}{x^2-3x}=\frac{x^2}{x\left(x-3\right)}+\frac{9-6x}{x\left(x-3\right)}\)

\(=\frac{\left(x-3\right)^2}{x\left(x-3\right)}=\frac{x-3}{x}\)

b/ đkxđ: \(x\ne0\)

\(\frac{x+2}{3x}+\frac{x-5}{5x}-\frac{x+8}{4x}\) \(=\frac{20x+40}{60x}+\frac{12x-60}{60x}-\frac{15x+120}{60x}\)

\(=\frac{17x-140}{60x}\)

516 x 2,15=1109,4

2,1655:50,4331

...

a, 516 x 2,15 = 1109,4

b, 2,1655 : 5 = 0,4331

c, \(\frac{15}{4}\)x \(\frac{8}{3}\)x \(\frac{16}{25}\)x \(\frac{1}{5}\)

= 10 x \(\frac{16}{25}x\frac{1}{5}\)

= \(\frac{32}{5}x\frac{1}{5}\)

= \(\frac{32}{25}\)

d, \(\frac{3}{7}:\frac{5}{4}x\frac{3}{5}\)

= \(\frac{3}{7}x\frac{4}{5}x\frac{3}{5}\)

= \(\frac{12}{35}x\frac{3}{5}\)

= \(\frac{36}{175}\)

a, 516x2,15=1109,4

b, 2,1655 : 5=0,4331

c, 15/4 x 8/3 x 16/25 x 1/5

=10x16/25 x 1/5

=6,4x1/5

=1.28

d, 3/7 : 5/4 x 3/5=12/35x3/5=36/175

(7 : 7  + 7) + (7 + 7 ) : 2 - 1 = 10 . đề là cho ghép các số nữa mà ?

tôi chịu em mới  lớp 2 thôi

1+2+3+4+5+6+7+8+9+10 = 55

1+2+3+4+5+6+7+8+9+10=55