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nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
Bài 1:
a; \(\dfrac{7}{8}\) + \(x\) = \(\dfrac{4}{7}\)
\(x\) = \(\dfrac{4}{7}\) - \(\dfrac{7}{8}\)
\(x\) = \(\dfrac{32}{56}\) - \(\dfrac{49}{56}\)
\(x=-\) \(\dfrac{49}{56}\)
Vậy \(x=-\dfrac{49}{56}\)
b; 6 - \(x\) = - \(\dfrac{3}{4}\)
\(x\) = 6 + \(\dfrac{3}{4}\)
\(x\) = \(\dfrac{24}{4}+\dfrac{3}{4}\)
\(x=\dfrac{27}{4}\)
Vậy \(x=\dfrac{27}{4}\)
c; \(\dfrac{1}{-5}\) + \(x\) = \(\dfrac{3}{4}\)
\(x\) = \(\dfrac{3}{4}\) + \(\dfrac{1}{5}\)
\(x=\dfrac{15}{20}\) + \(\dfrac{4}{20}\)
\(x=\dfrac{19}{20}\)
Vậy \(x=\dfrac{19}{20}\)
Bài 1:
d; - 6 - \(x\) = - \(\dfrac{3}{5}\)
\(x\) = - 6 + \(\dfrac{3}{5}\)
\(x=-\dfrac{30}{5}\) + \(\dfrac{3}{5}\)
\(x=-\dfrac{27}{5}\)
Vậy \(x=-\dfrac{27}{5}\)
e; - \(\dfrac{2}{6}\) + \(x\) = \(\dfrac{5}{7}\)
\(x\) = \(\dfrac{5}{7}\) + \(\dfrac{2}{6}\)
\(x\) = \(\dfrac{15}{21}\) + \(\dfrac{1}{3}\)
\(x=\dfrac{15}{21}\) + \(\dfrac{7}{21}\)
\(x=\dfrac{22}{21}\)
Vậy \(x=\dfrac{22}{21}\)
f; - 8 - \(x\) = - \(\dfrac{5}{3}\)
\(x\) = \(-\dfrac{5}{3}\) + 8
\(x\) = \(\dfrac{-5}{3}\) + \(\dfrac{24}{3}\)
\(x\) = \(\dfrac{-19}{3}\)
Vậy \(x=-\dfrac{19}{3}\)
a) 2(4x-8)-7(3+x)=|-4|.(3-2)
8x-16-21-7x=4
8x-7x=4+16+21
x=41
Vậy x=41
b) 8(x-|-7|)-6(x-2)=|-8|.6-50
8x-56-6x+12=8.6-50
8x-6x=48-50+56-12
2x=42
x=42:2
x=21
Vậy x=21
c) -7(5-x)-2(x-10)=15
-35+7x-2x+20=15
7x-2x=15+35-20
5x=30
x=30:5
x=6
Vậy x=6
d) 4(x-1)-3(x-2)=-|-5|
4x-4-3x+6=-5
4x-3x=-5+4-6
x=-7
Vậy x=-7
e) -4(x+1)+(89x-3)=24
-4x-4+89x-3=24
-4x+89x=24+4+3
85x=31
x=31/85
f) 5(x-30)-2(x+6)=9
5x-150-2x-12=9
5x-2x=9+150+12
3x=171
x=171:3
x=57
Vậy x=57
g) -3(x-5)+6(x+2)=9
-3x+15+6x+12=9
-3x+6x=9-15-12
3x=-18
x=-18:3
x=-6
Vậy x=-6
h) 7(x-9)-5(6-x)=-6+11x
7x-63-30+5x=-6+11x
7x+5x-11x=-6+62+30
x=86
Vậy x=86
k) 10(x-7)-8(x+5)=6.(-5)+24
10x-70-8x-40=-30+24
10x-8x=-30+24+70+40
2x=104
x=104:2
x=52
Vậy x=52
\(a,2.\left(x-5\right)-3.\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(x=-31-14\)
\(x=-45\)
\(b,5.\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36=12\)
\(3x=12+36\)
\(3x=48\)
\(x=16\)
\(c,-5.\left(2-x\right)+4.\left(x-3\right)=10.x-15\)
\(-10+5x+4x-12=10x-15\)
\(-6x-22=10x-15\)
\(-6x-10x=-15+22\)
\(-16x=7\)
\(x=-\frac{7}{16}\)
Câu d , e f tương tự nha
1/ Suy ra: -35 + 7x - 2x + 20 = 15
5x - 15 = 15
5x = 30
x = 6
2/ Suy ra: 4x - 20 - 3x - 21 = -19
x - 41 = -19
x = 22
3/ Suy ra: 8 - 4x + 3x - 15 = 14
-7 -x = 14
x = -7 -14
x = -21
4/ Suy ra: 7x - 63 - 30 + 5x = -6 + 11x
7x + 5x - 11x = -6 +63 + 30
x = 87
5/ Suy ra: -21x +35 + 14x - 28 = 28
-21x + 14x = 28 +28 - 35
-7x = 21
x= -3
6/ Suy ra: 20 - 5x + 7x - 14 = -2
2x = -8
x = -4
7/ Suy ra: 4x +15 -5x = 7
-x = -8
x = 8
8/ Suy ra: 5x - 35 +30 -10x = 20
-5x - 5 = 20
-5x = 25
x = -5
9/ Suy ra: 35 - 7x + 5x - 10 = 15
-7x + 5x = 15 +10 - 35
-2x = -10
x = 5
Học sinh nhẩm và ghi kết quả như sau:
3 x 4 = 12 2 x 6 = 12 4 x 3 = 12 5 x 6 = 30
3 x 7 = 21 2 x 8 = 16 4 x 7 = 28 5 x 4 = 20
3 x 5 = 15 2 x 4 = 8 4 x 9 = 36 5 x 7 = 35
3 x 8 = 24 2 x 9 = 18 4 x 4 = 16 5 x 9 = 45
3 x4 = 12
3 x7 = 21
3 x5 = 15
3 x8 =24
2 x 6= 12
2 x8 = 16
2 x4 =8
2 x9 =18
4 x3 =12
4 x7 =28
4 x9 =36
4 x4 =16
5 x6 =30
5 x4 =20
5 x7 =35
5 x9 =45
* f(x) = x2 + 2x3− 7x5 − 9 − 6x7 + x3 + x2 + x5 − 4x2 + 3x7
= (x2+ x2 – 4x2)+ (2x3 + x3 ) - (7x5 - x5 ) – 9 – (6x7 – 3x7)
= - 2x2 + 3x3 – 6x5 – 9 – 3x7
Sắp xếp theo thứ tự tăng của biến: f(x) = −9 − 2x2 + 3x3 − 6x5 − 3x7
* g(x) = x5 + 2x3 − 5x8 − x7 + x3 + 4x2 -5x7 + x4 − 4x2 − x6 – 12
= x5+ (2x3 + x3) - 5x8 – (x7+ 5x7) + (4x2 – 4x2 ) + x4 – x6 – 12
= x5 + 3x3 – 5x8 – 6x7 + x4 – x6 – 12
Sắp xếp theo thứ tự tăng của biến: g(x) = −12 + 3x3 + x4 + x5 – x6 − 6x7− 5x8
* h(x) = x + 4x5 − 5x6 − x7 + 4x3 + x2 − 2x7 + x6 − 4x2 − 7x7 + x.
= (x+ x) +4x5 – (5x6 – x6)- (x7 + 2x7+ 7x7) + 4x3+ (x2 – 4x2)
= 2x + 4x5 - 4x6 – 10x7 + 4x3 -3x2
Sắp xếp theo thứ tự tăng của biến: h(x) = 2x − 3x2 + 4x3 + 4x5 − 4x6 − 10x7