Tìm x
a . ( 17x + 23 ) : 12 = 9
b . 345 - ( 15x + 63 ) = 102
c . ( 11x - 23 ) . 73 = 5 . 75
Bài 2(2 điểm): Tính hợp lý (nếu có thể):
a) 1125 – ( 374 + 1125) + (-65 +374)
b) -23 . 63 + 23 . 21 – 58 . 23
c) -2003 + (-21+75 + 2003)
d) 942 – 2567 + 2563 – 1942
e) 12 - 12 + 11 + 10 - 9 + 8 - 7 + 5 - 4 + 3 + 2 -1
Tính hợp lý nếu có thể:
a) 1125-(374+1125) +(-65+374)
b) -23. 63+23. 21- 58. 23
c)-2003 +(-21+75+2003)
d)942-2567+2563-1942
e)12-12+11+10-9+8-7+5-4+3+2-1
a) 1125 - (374 + 1125) + (-65 + 374)
= 1125 - 374 - 1125 + (-65) + 374
= (1125 - 1125) + (-374 + 374) + (-65)
= 0 + 0 + (-65)
= -65
b) -23. 63 + 23 . 21 - 58 . 23
= 23 .(-63) + 23 . 21 - 58 . 23
= 23 . [(-63) + 21 - 58]
= 23 . (-100)
= -2300
c) -2003 + (-21 + 75 + 2003)
= -2003 + (-21) + 75 + 2003
= (-2003 + 2003) + (-21) + 75
= 0 + 54
= 54
d) 942 - 2567 + 2563 - 1942
= (942 - 1942) + (-2567 + 2563)
= -1000 + (-4)
= -1004
e) 12 - 12 + 11 + 10 - 9 + 8 - 7 + 5 - 4 + 3 + 2 - 1
= 0 + 11 + 1 + 1 + 1 + 3 + 1
= 18
A×345-34-(63:7-453+666)×{23-[63+(472-453)]}=??????/.
22/11x 22/17x 68/63 bằng , 5/14x7/13 26/25 bằng
63+ 45
73+23
Bài 2: Tính hợp lý (nếu có thể):
a) 1125 – ( 374 + 1125) + (-65 +374)
b) -23 . 63 + 23 . 21 – 58 . 23
c) -2003 + (-21+75 + 2003)
d) 942 – 2567 + 2563 – 1942
e) 12 - 12 + 11 + 10 - 9 + 8 - 7 + 5 - 4 + 3 + 2 -1
Bài 2:
a) 1125 - ( 374 + 1125) + (-65 +374)
= 1125 - 374 + 1125 + -65 + 374
= [ 1125 + (-1125)] + [(-374) + 374] + (-65)
= 0 + 0 + (-65)
= -65.
b) -23 . 63 + 23 . 21 - 58 . 23
= 23.(-63+23-58)
= 23.(-100)
= -2300.
c) -2003 + (-21+75+2003)
= -2003 + (-21) + 75 + 2003
= [(-2003) + 2003] + [(-21)+75]
= 0 + 54
= 54.
d) 942 - 2567 + 2563 + 1942
= [942 + (-1924)] + [(-2567)+2563]
= (-1000) + (-4)
= -1004.
e) 12 -12 + 11 + 10 - 9 + 8 - 7 + 5 - 4 + 3 + 2 -1
= (12 -12) + 11 + (10 - 9) + (8-7) + (5-4) + 3 + (2-1)
= 0 + 11 + 1 + 1 + 1 + 3 + 1
= 18.
Chúc bạn học tốt !!!
a, 1125 - ( 375 + 1125 ) + ( -65 + 374)
= 1125 - 1500 + 209
= 1125 - 1709
= -584
b, -23 .63 + 23.21 - 58.23
= -1449 + 483 - 1334
= -1449 + (-851)
= -2300
c,-2003 + ( -21 + 75 + 2003)
= -2003 + (-21) + 75 + 2003
= ( -2003 + 2003 ) + (-21 + 75 )
= 0 + 54
= 54
d, 942 - 2567 + 2563 - 1942
= (942 - 1942 ) + (2567 - 2563 )
= -1000 + 4
= -996
e, 12 - 12 + 11 + 10 - 9 + 8 - 7 + 5 -4 +3 -2 -1
=14
a.
=1125-1499+309=-374+309=-65
b.
= 23.(-63+21-58)=23.(-100)=-2300
c.
=-2003-21+75+2003
=-21+75=54
d.
=(942-1942)+(-2567)+2563=-1000+(-4)=-1004
e.
=(12-12)+11+(10-9)+(8-7)+(5-4)+3+(2-1)
=0+11+1+1+1+3+1=18
chúc bạn hk tốt
a)(6x^2+17x+12):(2x+3) b)(5x^2+13x-6):(5x-2) c)(-8x^2+22x-15):(2x-5) d)(14x^2-33x-5):(2x-5) e)(2x^3+7x^2+15x+6):(2x+1) f)(x^3+4x^2-11x-2):(x-2) g)(12x^3+2x^2+4x+3):(2x+1)
a: \(=\dfrac{6x^2+9x+8x+12}{2x+3}=\dfrac{3x\left(2x+3\right)+4\left(2x+3\right)}{2x+3}\)
=3x+4
b: \(=\dfrac{5x^2-2x+15x-6}{5x-2}\)
\(=\dfrac{x\left(5x-2\right)+3\left(5x-2\right)}{5x-2}=x+3\)
c: \(=\dfrac{-8x^2+20x+2x-5-10}{2x-5}=-4x+1+\dfrac{-10}{2x-5}\)
d: \(=\dfrac{14x^2-35x+2x-5}{2x-5}=\dfrac{7x\left(2x-5\right)+\left(2x-5\right)}{2x-5}\)
=7x+1
e: \(=\dfrac{2x^3+x^2+6x^2+3x+12x+6}{2x+1}\)
\(=\dfrac{x^2\left(2x+1\right)+3x\left(2x+1\right)+6\left(2x+1\right)}{2x+1}=x^2+3x+6\)
f: \(=\dfrac{x^3-2x^2+6x^2-12x+x-2}{x-2}=x^2+6x+1\)
g: \(=\dfrac{12x^3+6x^2-4x^2-2x+6x+3}{2x+1}=6x^2-2x+3\)
tìm x
a)x^2-x-12=0
b)x^2+3x-18=0
c)8x^2+30x+7=0
d)x^3-11x^2+30x=0
e)x^3-7x^2+15x-25=0
giúp mk vs ah!!!!!
a) Ta có: \(x^2-x-12=0\)
\(\Leftrightarrow\left(x-4\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)
b) Ta có: \(x^2+3x-18=0\)
\(\Leftrightarrow\left(x+6\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-6\\x=3\end{matrix}\right.\)
: Tìm x, biết. a) 7(x – 5) + 2 = 51 k) 2412 : (3x + 147) = |-38| + (-26) b) (43 – 11x).53 = 4.54 l) 4824 : (4x + 137) = |-59| + (-35) c) |-123| - 5(x – 3) = (-28) + 66 m) 7x-4 .6 = 2058 d) 42 – 3(5x + 1) = 35 : 33 n) 27 - |x| = 2.(52 – 24 ) e) |x| - 15 = - 5 o) 3.2x + 2x+3 = 44 f) 2x – 2828 : 14 = 308 p) 95 – 5(x + 3) = 75 : 73 + 21 g) 3x + 3x+1 + 3x+2 = 1053 q) 1300 : [110 – (x – 7)] = 26 h) (11x – 23 ).93 = 4.94 r) 5.(12 – 3x) – 20 = 10
a) 7(x - 5) + 2 = 51
\(\Leftrightarrow\) 7(x - 5) = 51 - 2
\(\Leftrightarrow\) 7(x - 5) = 49
\(\Leftrightarrow\) x - 5 = 49 : 7
\(\Leftrightarrow\) x - 5 = 7
\(\Leftrightarrow\) x = 7 + 5
\(\Leftrightarrow\) x = 12.
Vậy x = 12.
k) 2412 : (3x + 147) = |-38| + (-26)
\(\Leftrightarrow\) 2412 : (3x + 147)= 38 + (-26)
\(\Leftrightarrow\) 2412 : (3x + 147)= 12
\(\Leftrightarrow\) 3x + 147 = 2412 : 12
\(\Leftrightarrow\) 3x + 147 = 201
\(\Leftrightarrow\) 3x = 201 - 147
\(\Leftrightarrow\) 3x = 54
\(\Leftrightarrow\) x = 54 : 3
\(\Leftrightarrow\) x = 18.
Vậy x = 18.
I) 4824 : (4x + 137) = |-59| + (-35)
\(\Leftrightarrow\) 4824 :(4x + 137) = 59 + (-35)
\(\Leftrightarrow\) 4824 :(4x + 137) = 24
\(\Leftrightarrow\) 4x + 137 = 4824 : 24
\(\Leftrightarrow\) 4x + 137 = 201
\(\Leftrightarrow\) 4x = 201 - 137
\(\Leftrightarrow\) 4x = 64
\(\Leftrightarrow\) x = 64 : 4
\(\Leftrightarrow\) x = 16.
Vậy x = 16.
c) |-123| - 5(x - 3) = (-28) + 66
\(\Leftrightarrow\) 123 - 5(x - 3) = 38
\(\Leftrightarrow\) 5(x - 3) = 123 - 38
\(\Leftrightarrow\) 5(x - 3) = 85
\(\Leftrightarrow\) x - 3 = 85 : 5
\(\Leftrightarrow\) x - 3 = 17
\(\Leftrightarrow\) x = 17 + 3
\(\Leftrightarrow\) x = 20.
Vậy x = 20.
m) 7x - 4 . 6 = 2058
\(\Leftrightarrow\) 7x - 24 = 2058
\(\Leftrightarrow\) 7x = 2058 + 24
\(\Leftrightarrow\) 7x = 2082
\(\Leftrightarrow\) x = 2082 : 7
\(\Leftrightarrow\) x = \(\frac{2058}{7}\).
Vậy x = \(\frac{2058}{7}\).
Phần b) ra phân số nên mình để mai làm và cả những bài còn lại nữa.
Chúc bạn học tốt !!!
---------------NHANH NHA MK ĐANG CẦN GẤP--------------
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