2/15-7/10=
(-5)-2/7=
2,5-(-3/4)=
Làm giúp mik vs!!!THANK
a, 6,5 - 9/4 :| x + 1/3 |= 2
b, 11/4 + 3/2: | 4x - 1/ 5|= 7/2
c, 15/4 - 2,5 :| 3/4x + 1/2|= 3
Mn giúp mik vs mik đang cần gấp
2/1*3+2/3*5+2/5*7+......+2/97*99
giải giúp mik vs
thank
\(\dfrac{2}{1\cdot3}+\dfrac{2}{3\cdot5}+\dfrac{2}{5\cdot7}+...+\dfrac{2}{97\cdot99}\)
\(=1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{97}-\dfrac{1}{99}\)
\(=1-\dfrac{1}{99}=\dfrac{98}{99}\)
tìm số nguyên x biết:
a,-5.(-x+7)-3.(-x-5)=-4.(12-x)+48
b;-2.(15-3x)-4.(7x+8)=-5-9.(-2x+1)
c,7.(-x-7)-5.(-x-3)=12.(3-x)
d,5.(-3x-7)-4.(-2x-11)=7.(4x+10)+9
GIÚP MIK VS NHÉ AI LÀM ĐC HẾT MÀ ĐÚNG MIK SẼ CHO 1 TICK
phân tích đa thức thành nhân tử
1.(x+2)(x+3)(x+4)(x+5)-24
2.(x-1)(x-3)(x-5)(x-7)-20
3.x(x-1)(x-1)(x+2)-3
4.(x-7)(x-5)(x-4)(x-2)-72
5.(x^2+6x+8)(x^2-8x+15)-24
6.(x^2-6x+5)(x^2-10x+21)-20
7.(x^2+5x+6)(x^2-15x+56)-144
#Mn làm giúp mik vs#
#thank kiu#
phân tích đa thức thành nhân tử
1.(x+2)(x+3)(x+4)(x+5)-24
2.(x-1)(x-3)(x-5)(x-7)-20
3.x(x-1)(x-1)(x+2)-3
4.(x-7)(x-5)(x-4)(x-2)-72
5.(x^2+6x+8)(x^2-8x+15)-24
6.(x^2-6x+5)(x^2-10x+21)-20
7.(x^2+5x+6)(x^2-15x+56)-144
#Mn làm giúp mik vs#
#thank kiu#
1) \(\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-24\)
\(=\left(x+2\right)\left(x+5\right)\left(x+3\right)\left(x+4\right)-24\)
\(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-24\)
Đặt \(x^2+7x=t\)
\(\Rightarrow BT=\left(t+10\right)\left(t+12\right)-24\)
\(=t^2+22x+96=\left(t+11\right)^2-25\ge-25\)
Vậy GTNN của bt là - 25\(\Leftrightarrow x^2+7x+11=0\)
\(\Delta=7^2-4.11=5\)
\(\orbr{\begin{cases}x_1=\frac{-22+\sqrt{5}}{2}\\x_2=\frac{-22-\sqrt{5}}{2}\end{cases}}\)
2) \(\left(x-1\right)\left(x-3\right)\left(x-5\right)\left(x-7\right)-20\)
\(=\left(x-1\right)\left(x-7\right)\left(x-3\right)\left(x-5\right)-20\)
\(=\left(x^2-8x+7\right)\left(x^2-8x+15\right)-20\)
Đặt \(x^2-8x=t\)
\(\RightarrowĐT=\left(t+7\right)\left(t+15\right)-20\)
\(=t^2+22t+85=\left(t+11\right)^2-36\ge-36\)
Vậy GTNN của bt là - 36\(\Leftrightarrow x^2-8x+11=0\)
\(\Delta=\left(-8\right)^2-4.11=20\)
\(\orbr{\begin{cases}x_1=\frac{-22-\sqrt{20}}{2}\\x_2=\frac{-22+\sqrt{20}}{2}\end{cases}}\)
Nhầm, lộn tìm GTNN
a) \(\left(t+11\right)^2-25=\left(x^2+7x-16\right)\left(x^2+7x+36\right)\)
b) \(\left(x^2-8x+5\right)\left(x^2-8x+16\right)\)
\(=\left(x^2-8x+5\right)\left(x-4\right)^2\)
phân tích đa thức thành nhân tử
1.(x+2)(x+3)(x+4)(x+5)-24
2.(x-1)(x-3)(x-5)(x-7)-20
3.x(x-1)(x-1)(x+2)-3
4.(x-7)(x-5)(x-4)(x-2)-72
5.(x^2+6x+8)(x^2-8x+15)-24
6.(x^2-6x+5)(x^2-10x+21)-20
7.(x^2+5x+6)(x^2-15x+56)-144
#Mn làm giúp mik vs#
#thank kiu#
phân tích đa thức thành nhân tử
1.(x+2)(x+3)(x+4)(x+5)-24
2.(x-1)(x-3)(x-5)(x-7)-20
3.x(x-1)(x-1)(x+2)-3
4.(x-7)(x-5)(x-4)(x-2)-72
5.(x^2+6x+8)(x^2-8x+15)-24
6.(x^2-6x+5)(x^2-10x+21)-20
7.(x^2+5x+6)(x^2-15x+56)-144
#Mn làm giúp mik vs#
#thank kiu#
a)(3/10-4/15-7/20).5/19 / (1/14+1/7-(-3/35)).(-4/3)
b)(1+2+3+...+100).(1/3-1/5-1/7-1/9).(6,3.12-21.3,6) / 1/2+1/3+1/4+...+1/100
LÀM GIÚP MIK VỚI Ạ MIK GẤP LẮM RỒI
Bài 1: Tính nhanh
a,6/1*3*7+6/3*7*9+6/7*9*13+6/9*13*15+6/13*15*19
b,1/1*3*7+1/3*7*9+1/7*9*13+1/9*13*15+1/13*15*19
c,1/2*4*6+1/4*6*8+1/6*8*10+1/8*10*12*14+...+1/96*98*100
d,5/1*5*8+5/5*8*12+5/8*12*15+...+5/33*36*40
giúp mik vs các bạn anh chị gì đó ghi hết cách làm và kết quả ra nha
Lưu ý:* là dấu nhân / là phần
\(a,=\frac{7-1}{1.3.7}+\frac{9-3}{3.7.9}+\frac{13-7}{7.9.13}+\frac{15-9}{9.13.15}\)\(+\frac{19-13}{13.15.19}\)
\(=\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.13}+\frac{1}{9.13}-\frac{1}{13.15}+\frac{1}{13.15}-\frac{1}{15.19}\)
\(=\frac{1}{1.3}-\frac{1}{15.19}=\frac{95}{285}-\frac{1}{285}=\frac{94}{285}\)
\(b,=\frac{1}{6}.\left(\frac{6}{1.3.7}+\frac{6}{3.7.9}+\frac{6}{7.9.13}+\frac{6}{9.13.15}+\frac{6}{13.15.19}\right)\)
làm giống như trên
\(c,=\frac{1}{8}.\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{50-48}{48.49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{48.49}-\frac{1}{49.50}\right)\)
\(=\frac{1}{16}.\left(\frac{1}{2}-\frac{1}{2450}\right)=\frac{1}{16}.\left(\frac{1225}{2450}-\frac{1}{2450}\right)=\frac{153}{4900}\)
\(d,=\frac{5}{7}.\left(\frac{7}{1.5.8}+\frac{7}{5.8.12}+\frac{7}{8.12.15}+...+\frac{7}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{8-1}{1.5.8}+\frac{12-5}{5.8.12}+\frac{15-8}{8.12.15}+...+\frac{40-33}{33.36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{1.5}-\frac{1}{5.8}+\frac{1}{5.8}-\frac{1}{8.12}+\frac{1}{8.12}-\frac{1}{12.15}+...+\frac{1}{33.36}-\frac{1}{36.40}\right)\)
\(=\frac{5}{7}.\left(\frac{1}{5}-\frac{1}{1440}\right)=\frac{5}{7}.\left(\frac{288}{1440}-\frac{1}{1440}\right)=\frac{41}{288}\)
P/S: . là nhân nha
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