ra 34 và - 20 

mk làm rùi đó ,bài dưới ế ,rõ ràng rành mạch lên pạn mk nha 

|7- x|=(-13)-5.(-8)

|7- x|=144

7- x=144

      x=7-144

        x=(-137)

Vậy : x=(-137); x=137

Bài 1

1.\(x\left(x+3\right)\)

\(=x^2+3x\)

2.\(3x\left(x+2\right)\)

\(=3x^2+6x\)

3,\(x^2\left(3x-1\right)\)

\(=3x^3-x^2\)

4.\(-5x^3\left(3x^2-7\right)\)

\(=-15x^5+35x^3\)

5.\(3x\left(5x^2-2x-1\right)\)

\(=15x^3-6x^2-3x\)

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

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

7.\(\left(x^2+2x-3\right).\left(-x\right)\)

\(=-x^3-2x^2+3x\)

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

\(=-8x^5+16x^7-12x^3\)

9.\(-5x^2\left(3x^2-2x+1\right)\)

\(=-15x^4+10x^3-5x^2\)

10.\(-4x^5\left(x^3-4x^2+7x-3\right)\)

\(=-4x^8+16x^7-28x^6+12x^5\)

11.\(\left(x+2\right)\left(x+3\right)\)

\(=x^2+3x+2x+6\)

12.\(\left(x-7\right)\left(x-5\right)\)

\(=x^2-5x-7x+35\)

13.\(\left(3x+5\right)\left(2x-7\right)\)

\(=6x^2-21x+10x-35\)

14.\(\left(x-3\right)\left(x^2-2x-1\right)\)

\(x^3-2x^2-x-3x^2+6x+3\)

15.\(\left(2x-1\right)\left(x^2-5x+3\right)\)

\(=2x^3-10x^2+6x-x^2+5x-3\)

16.\(\left(x-5\right)\left(-x^2+x-1\right)\)

\(=-x^3+x^2-x+5x^2-5x+5\)

17,\(\left(\dfrac{1}{2}x+3\right)\left(2x^2-4x-6\right)\)

\(=x^3-2x^2-3x+6x^2-12x-18\)

P/s:mình làm hơi tắt tại bài dài quá:))

Bài 2

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

\(=5x^2-3x^2+2\)

\(=2x^2+2\)

2.\(-2x^2+3\left(x^2+2\right)\)

\(=-2x^2+3x^2+6\)

\(=x^2+6\)

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

\(=-4x^2+2x-4x^2+20x\)

\(=22x\)

4.\(3x\left(x-5\right)-5x\left(x+7\right)\)

\(=3x^2-15x-5x^2-35x\)

\(=-2x^2-50x\)

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

\(=-9x^2+12x+6x^2+2x\)

\(=-3x^2+14x\)

6.\(x\left(x^2+x+1\right)-x\left(2x^2+1\right)\)

\(=x^3+x^2+x-2x^3-x\)

\(=-x^3+x^2\)

7.\(x\left(2x^2-3\right)-x^2\left(5x+1\right)+x^2\)

\(=2x^3-3x-5x^3-x^2+x^2\)

\(=-3x^3-3x\)

8.\(4x\left(x^2-x+1\right)-x\left(3x-2x-5\right)\)

\(=4x^3-4x^2+4x-3x^2+2x^2+5x\)

\(=4x^3-5x^2+9x\)

9.\(4x\left(x^2-x+1\right)+\left(x-1\right)\left(x^2-x\right)\)

\(=4x^3-4x^2+4x+x^3-x^2-x^2+x\)

\(=5x^3-6x^2+5x\)

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

\(=2x^2+8x-3x-12+-x^2+2x+x-2\)

\(=x^2+8x-14\)

11.\(\left(-x+5\right)\left(x+3\right)+\left(2x-1\right)\left(x+3\right)\)

\(=-x^2-3x+5x+15+2x^2+6x-x-3\)

\(=x^2+7x+12\)

12.\(\left(x+3\right)\left(x-1\right)-4x\left(x^2-2x\right)\)

\(=x^2-x+3x-3-4x^3+8x^2\)

\(=9x^2+2x-3-4x^3\)

1.Tính  góc A=180-75=105 độ

suy ra góc C=180- góc A-góc B=180-50-105=....

câu 1 góc A=180-75=105 độ

lại có tổng 3 góc trong 1 tam giác =180 độ nên goc C=180-50-105=25 do

câu 2 có ý=x-3 rồi thế vào phương trình x2​ -x*(x-3)+5=-13 nen suy ra x=6

a, 37/9 - Y = 6/5 x 15/16

37/9 - Y = 9/8

Y = 37/9 - 9/8

Y = 296/72 - 81/72

Y = 215/72

b, Y x 3/15 = 4/5 - 2/3

 Y x 3/15 =  2/15

Y = 2/15 : 3/15

Y = 2/15 x 15/3

Y = 2/3

`a)37/9-y=6/5xx15/16`

`37/9-y=9/8`

`y=37/9-9/8`

`y=296/72-81/72=215/72`

`b)y xx3/15=4/5-2/3`

`y xx3/15=12/15-10/15`

`y xx3/15=2/15`

`y=2/15:3/15`

`y=2/15xx15/3=2/3`

|7-x|=-13-5.(-8)

|7-x|=-13-(-40)

|7-x|=27

TH1:7-x=27

          x=-20

TH2:7-x=-27

          x=34

Vậy x=-20;x=34

ra 34 và -20 

ở bài dưới cùng đó ,

pạn mk nha 

| 7-x| = 27

=> 7-x=27 <=> x= -20

hoặc 7-x=-27 <=> 34 

k nhaaa

gúp tôi giải bài toán này 

tìm x 

5x5 + = 100- 36

|7 - x| = -13 - 5(-8)

=> |7 - x| = -13 - (-40)

=> |7 - x| = -13 + 40 = 27

=> 7 - x thuộc {-27; 27}

=> x thuộc {34; -20}

37,-37

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`7,`

`a, B+A=4x-2x^2+3`

`-> B=(4x-2x^2+3)-A`

`-> B=(4x-2x^2+3)-(x^2-2x+1)`

`B=4x-2x^2+3-x^2+2x-1`

`B=(-2x^2-x^2)+(4x+2x)+(3-1)`

`B=-3x^2+6x+2`

`b, C-A=-x+7`

`-> C=(-x+7)+A`

`-> C=(-x+7)+(x^2-2x+1)`

`-> C=-x+7+x^2-2x+1`

`C=x^2+(-x-2x)+(7+1)`

`C=x^2-3x+8`

`c,`

`A-D=x^2-2`

`-> D= A- (x^2-2)`

`-> D=(x^2-2x+1)-(x^2-2)`

`D=x^2-2x+1-x^2+2`

`D=(x^2-x^2)-2x+(1+2)`

`D=-2x+3`

`6,`

`a,`

`P+Q=4x-2x^2+3`

`-> Q=(4x-2x^2+3)-P`

`-> Q=(4x-2x^2+3)-(3x^2+x-1)`

`Q=4x-2x^2+3-3x^2-x+1`

`Q=(-2x^2-3x^2)+(4x-x)+(3+1)`

`Q=x^2+3x+4`

`b,`

`x^2-5x+2-P=H`

`-> H= (x^2-5x+2)-(3x^2+x-1)`

`H=x^2-5x+2-3x^2-x+1`

`H=(x^2-3x^2)+(-5x-x)+(2+1)`

`H=-4x^2-6x+3`

`c,`

`P-R=5x^2-3x-4`

`-> R= P- (5x^2-3x-4)`

`-> R=(3x^2+x-1)-(5x^2-3x-4)`

`R=3x^2+x-1-5x^2+3x+4`

`R=(3x^2-5x^2)+(x+3x)+(-1+4)`

`R=-2x^2+4x+3`

ảnh kia nhiều người lắm like thế :)

thì ai cũng chịu mà