Bài 1: Thực hiện các phép tính sau:
A=( 2$\frac{2}{5}$ -3$\frac{5}{9}$ ) : ( 3$\frac{30}{21}$ -1$\frac{3}{7}$ )
B= 3$\frac{1}{2}$ + 15$\frac{4}{9}$ : $\frac{26}{7}$ – 2$\frac{4}{9}$ : 3$\frac{5}{7}$
Bài 5: Tìm x thuộc Z , biết :
a)
$\frac{5}{21}$ + $\frac{-3}{7}$ < $\frac{x}{21}$ < $\frac{-2}{7}$ + $\frac{8}{21}$
b)
1+ $\frac{-1}{60}$ + $\frac{19}{120}$ < $\frac{x}{36}$ + $\frac{-1}{60}$ < $\frac{58}{90}$ + $\frac{59}{72}$ + $\frac{-1}{60}$
Bài 6:
a) (2$\frac{1}{3}$ + 3$\frac{1}{2}$) x = -4$\frac{1}{6}$ + 3$\frac{1}{7}$
b) ($\frac{1}{2} x - 1)^{3}$ = $\frac{-1}{8}$
c) $\frac{-x}{2}$ + $\frac{2x}{3}$ + $\frac{x+1}{4}$ + $\frac{2x+1}{6}$ = $\frac{8}{3}$
d) $\frac{3}{2x+1}$ + $\frac{10}{4x+2}$ - $\frac{6}{6x+3}$ = $\frac{12}{26}$
Bài 1:
+, A = (2$\frac{2}{5}$ – 3$\frac{5}{9}$) : (3$\frac{30}{21}$ – 1$\frac{3}{7}$)
⇔ A = ($\frac{12}{5}$ – $\frac{32}{9}$) : ($\frac{31}{7}$ – $\frac{10}{7}$ )
⇔ A = $\frac{108-160}{45}$ : $\frac{31-10}{7}$
⇔ A = $\frac{-52}{45}$ : 3
⇔ A = $\frac{-52}{45}$ × $\frac{1}{3}$
⇔ A = $\frac{-52}{135}$
+, B = 3$\frac{1}{2}$ + 15$\frac{4}{9}$ : $\frac{26}{7}$ – 2$\frac{4}{9}$ : 3$\frac{5}{7}$
⇔ B = $\frac{7}{2}$ + $\frac{139}{9}$ : $\frac{26}{7}$ – $\frac{22}{9}$ : $\frac{26}{7}$
⇔ B = $\frac{7}{2}$ + $\frac{139}{9}$ x $\frac{7}{26}$ – $\frac{22}{9}$ x $\frac{7}{26}$
⇔ B = $\frac{7}{2}$ + $\frac{7}{26}$ x ($\frac{139}{9}$ – $\frac{22}{9}$)
⇔ B = $\frac{7}{2}$ + $\frac{7}{26}$ x 13
⇔ B = $\frac{7}{2}$ + $\frac{7}{2}$
⇔ B = 7
Bài 5:
a, $\frac{5}{21}$ + $\frac{-3}{7}$ < $\frac{x}{21}$ < $\frac{-2}{7}$ + $\frac{8}{21}$
⇔ $\frac{5}{21}$ – $\frac{9}{21}$ < $\frac{x}{21}$ < $\frac{-6}{21}$ + $\frac{8}{21}$
⇔ $\frac{-4}{21}$ < x < $\frac{2}{21}$
⇒ $\frac{x}{21}$ = {$\frac{-3}{21}$; $\frac{-2}{21}$; $\frac{-1}{21}$; $\frac{0}{21}$; $\frac{1}{21}$}
⇒ x = {-3; -2; -1; 0; 1}
b, 1 + $\frac{-1}{60}$ + $\frac{19}{120}$ < $\frac{x}{36}$ + $\frac{-1}{60}$ < $\frac{58}{90}$ + $\frac{59}{72}$ + $\frac{-1}{60}$
⇔ 1 + $\frac{-1}{60}$ + $\frac{19}{120}$ < $\frac{x}{36}$ – $\frac{1}{60}$ < $\frac{58}{90}$ + $\frac{59}{72}$ + $\frac{-1}{60}$
⇔ 1 + $\frac{-1}{60}$ + $\frac{19}{120}$ + $\frac{1}{60}$< $\frac{x}{36}$ < $\frac{58}{90}$ + $\frac{59}{72}$ + $\frac{-1}{60}$ + $\frac{1}{60}$
⇔ 1 + $\frac{19}{120}$ < $\frac{x}{36}$ < $\frac{58}{90}$ + $\frac{59}{72}$
⇔ $\frac{139}{120}$ < $\frac{x}{36}$ < $\frac{527}{360}$
⇔ $\frac{417}{360}$ < $\frac{x.10}{360}$ < $\frac{527}{360}$
⇒ $\frac{x.10}{360}$ = {$\frac{420}{360}$; $\frac{430}{360}$; $\frac{440}{360}$; $\frac{450}{360}$; $\frac{460}{360}$; $\frac{470}{360}$; $\frac{480}{360}$; $\frac{490}{360}$; $\frac{500}{360}$; $\frac{510}{360}$; $\frac{520}{360}$}
⇔ $\frac{x}{36}$ = {$\frac{42}{36}$; $\frac{43}{36}$; $\frac{44}{36}$; $\frac{45}{36}$; $\frac{46}{36}$; $\frac{47}{36}$; $\frac{48}{36}$; $\frac{49}{36}$; $\frac{50}{36}$; $\frac{51}{36}$; $\frac{52}{36}$}
⇒ x = {42; 43; 44; …; 52}
Bài 6:
a, (2$\frac{1}{3}$ + 3$\frac{1}{2}$)x = -4$\frac{1}{6}$ + 3$\frac{1}{7}$
⇔ $\frac{35}{6}$x = $\frac{-43}{42}$
⇔ x = $\frac{-43}{245}$
b, ($\frac{1}{2}$x – 1)³ = -$\frac{1}{8}$
⇔ $\frac{1}{2}$x – 1 = -$\frac{1}{2}$
⇔ $\frac{1}{2}$x = $\frac{1}{2}$
⇔ x = 1
c, $\frac{-x}{2}$ + $\frac{2x}{3}$ + $\frac{x+1}{4}$ + $\frac{2x+1}{6}$ = $\frac{8}{3}$
⇔ $\frac{-6x}{12}$ + $\frac{8x}{12}$ + $\frac{3x+3}{12}$ + $\frac{4x+2}{12}$ = $\frac{32}{12}$
⇒ -6x + 8x + 3x + 3 + 4x + 2 = 32
⇔ 9x = 27
⇔ x = 3
d,Phần này mk k biết làm, mk chỉ giúp được bạn nhiêu đó thôi
Kết quả: x = 6
Đáp án:
Giải thích các bước giải:
bài 1 A=-52/45:3=-52/125
B=7/2+136/9:26/7-22/9:26/7
=7/2+476/117-77/117
=7/2+113/39
=499/78
bài 2
a,5/21+-3/7=-4/21
-2/7+8/21=2/21
-3/21;-2/21;-1/21;1/21
để x thuộc z lớn hơn -4/21 và nhỏ hơn 2/21 thì x=-3/21;-2/21;-1/21;1/21
bài 3
a,x=-43/245