Tìm x
(4x-7)2=11
Tìm x
(4x.7)2 =11
(4x.7)2=11 ➩ 42.x2.72=11➩16.x2.49=11➩784.x2=11➩x2=\(\dfrac{11}{784}\)➩x=\(\sqrt{\dfrac{11}{784}}\)
hoặc x=\(-\sqrt{\dfrac{11}{784}}\)
Tìm x,y,z biết : |x + 11/7|+|x + 2/17|+|x + 4/17|=4x
tìm x biết:
a)(2x+2)(2x-2)-4x(x+5)=8
b)(4x+5)(4x-5)-8x(2x-7)=11
c)(1/2x-3)(1/2x+3)-1/4x(x+5)=11/2
d)(3x+2)(3x-2)-4x(x+2-5x2=18
\(a.x=-0,6\)
\(c.x=-11,6\)
Pt nhju ak!!!
Tìm x
(4x-7)2=11
(*Xin lỗi đề hồi nãy ghi lộn)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{\sqrt{11}+7}{4}\\x=\dfrac{-\sqrt{11}+7}{4}\end{matrix}\right.\)
Tìm x
\(a.\dfrac{\sqrt{5x+7}}{x+3}=4\)
\(b.\left(7+\sqrt{x}\right).\left(8-\sqrt{x}\right)=11+x\)
\(c.\sqrt{2x^2+2-4x}=6\)
Tìm giá trị lớn nhất của các biểu thức sau
a) I =(1-x)(x+2)(x+3)(x+6) +2021
b)K =(7-x)(x-5)(x-4)(x-2) +102
c) M = - (2x+1)2(4x+1)(4x+3)-11
\(I=-\left(x-1\right)\left(x+6\right)\left(x+2\right)\left(x+3\right)+2021\)
\(=-\left(x^2+5x-6\right)\left(x^2+5x+6\right)+2021\)
\(=-\left[\left(x^2+5x\right)^2-6^2\right]+2021\)
\(=-\left(x^2+5x\right)^2+2057\le2057\)
\(I_{max}=2057\) khi \(x^2+5x=0\)
\(K=-\left(x-2\right)\left(x-7\right)\left(x-5\right)\left(x-4\right)+102\)
\(=-\left(x^2-9x+14\right)\left(x^2-9x+20\right)+102\)
\(=-\left(x^2-9x+14\right)\left(x^2+9x+14+6\right)+102\)
\(=-\left[\left(x^2-9x+14\right)^2+6\left(x^2-9x+14\right)\right]+102\)
\(=-\left[\left(x^2-9x+14\right)+6\left(x^2-9x+14\right)+9-9\right]+102\)
\(=-\left(x^2-9x+17\right)^2+111\le111\)
\(K_{max}=111\) khi \(x^2-9x+17=0\)
\(M=-\left(4x^2+4x+1\right)\left(16x^2+16x+3\right)-11\)
Đặt \(4x^2+4x+1=t\Rightarrow16x^2+16x=4t-4\)
\(\Rightarrow M=-t\left(4t-4+3\right)-11\)
\(M=-4t^2+t-11\)
\(M=-4\left(t-\dfrac{1}{8}\right)^2-\dfrac{175}{16}\le-\dfrac{175}{16}\)
\(M_{max}=-\dfrac{175}{16}\) khi \(t=\dfrac{1}{8}\)
Tìm x:
a) 3/4x + 2/5x=1
b) ( x-9/11)( x-25/31)=0
c) x-3/7:9/14=7/3
Ai giúp đc k ah?!
a,x.(3\4+2\5)=1
x.20\23=1
x=1:20\23
x=20\23
b,x-9\11=0 hoặc x-25\31=0
x=9\11 x=25\31
c,x-3\7.9\14=7\3
x-2\3=7\3
x=7\3+2\3
x=9\3
x=3
1.tìm x
a) 4.(2x + 7) - 3.(3x - 2) = 24
b) 2.(x - 1) + 3.(x - 2) = x - 4
c) [124 - (20 - 4x)] : 30 + 7 = 11
a. 4(2x+7)-3(3x-2)=24
=> 8x+28-9x+6=24
=> -x+34=24
=> -x=-10=> x=10
b. 2(x-1)+3(x-2)=x-4
=> 2x-2+3x-6=x-4
=> 5x-8=x-4
=> 5x-x=-4+8
=> 4x=4=> x=1
c. [124-(20-4x)]:30+7=11
=> (124-20+4x):30=4
=> (104+4x):30=4
=> 104+4x=120
=> 4x=96 => x=24
Tìm x:
a) x^2-4x-7=0
b) x^2-x-11=0
c) 2x^4-6x^3+x^2+6x-3=0
a) \(x^2-4x-7=0\)
Ta có: \(\Delta=4^2+4.28=128,\sqrt{\Delta}=\sqrt{128}\)
pt có 2 nghiệm:
\(x_1=\frac{4+\sqrt{128}}{2}\);\(x_2=\frac{4-\sqrt{128}}{2}\)
b) \(x^2-x-11=0\)
Ta có: \(\Delta=1^2+4.11=45,\sqrt{\Delta}=\sqrt{45}\)
pt có 2 nghiệm:
\(x_1=\frac{1+\sqrt{45}}{2}\)\(x_2=\frac{1-\sqrt{45}}{2}\)