Bài 1:1.Thực hiện phép tính:3√49-1,5(√4-1/3)2+1/4:(-1/√16+1/2)
2.Tìm x biết:5x-(-2x-0,3)=2,4
Các bn lm giúp mk
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\(a,5^{n+1}-4.5^n=5^n\left(5-4\right)=5^n\)
B2:
\(4\left(18-5x\right)-12.\left(3x-7\right)=15\left(2x-16\right)-6\left(x+14\right)\)
\(\Rightarrow72-20x-36x+84=30x-240-6x-84\)
\(\Rightarrow156-56x-24x+324=0\)
\(\Rightarrow480-80x=0\)
\(\Rightarrow80x=480\)
\(\Rightarrow x=6\)
Vậy x=6
Bài 1:
\(a,5^{n+1}-4.5^n=5^n\left(5-4\right)\)
\(=5^n.1\)
\(=5^n\)
\(b,6^2.6^4-4^3.\left(3^6-1\right)=6^6-\left(2^2\right)^3\left(3^6-1\right)\)
\(=6^6-2^6\left(3^6-1\right)\)
\(=6^6-6^6+2^6\)
\(=2^6\)
\(=64\)
Bài 2:
\(a,4.\left(18-5x\right)-12.\left(3x-7\right)=15.\left(2x-16\right)-6.\left(x+14\right)\)
\(\Rightarrow72-20x-36x+84=30x-240-6x-84\)
\(\Rightarrow30x-6x+20x+36x=72+84+240+84\)
\(\Rightarrow80x=6372\)
\(\Rightarrow x=79,65\)
1) (x2 - 2x - 1)(x - 3)
= x2(x - 3) - 2x(x - 3) - 1(x - 3)
= x3 - 3x2 - 2x2 + 6x - x + 3
= x3 - 5x2 + 5x + 3
2. (-x + 4)(-x2 + 4x - 1)
= -x(-x2 + 4x - 1) + 4(-x2 + 4x - 1)
= x3 - 4x2 + x - 4x2 + 16x - 4
= x3 - 8x2 + 17x - 4
3 ) (2x - 1)(x2 - 5x + 3)
= 2x(x2 - 5x + 3) - 1(x2 - 5x + 3)
= 2x3 - 10x2 + 6x - x2 + 5x - 3
= 2x3 - 11x2 + 11x - 3
Bài làm :
1) (x2 - 2x - 1)(x - 3)
= x2(x - 3) - 2x(x - 3) - 1(x - 3)
= x3 - 3x2 - 2x2 + 6x - x + 3
= x3 - 5x2 + 5x + 3
2) (-x + 4)(-x2 + 4x - 1)
= -x(-x2 + 4x - 1) + 4(-x2 + 4x - 1)
= x3 - 4x2 + x - 4x2 + 16x - 4
= x3 - 8x2 + 17x - 4
3 ) (2x - 1)(x2 - 5x + 3)
= 2x(x2 - 5x + 3) - 1(x2 - 5x + 3)
= 2x3 - 10x2 + 6x - x2 + 5x - 3
= 2x3 - 11x2 + 11x - 3
Bài 1:
a) \(3x\left(5x^2-2x+1\right)\)
\(=15x^3-6x^2+3x\)
b) \(\left(x^2-1\right)\left(x^2+2x\right)\)
\(=x^2\left(x^2-1\right)+2x\left(x^2-1\right)\)
\(=x^4-x^2+2x^3-2x\)
\(=x^4+2x^3-x^2-2x\)
Bài 2:
a) \(3x^2=2x\)
\(\Leftrightarrow3x^2-2x=0\)
\(\Leftrightarrow x\left(3x-2\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\3x-2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=\frac{2}{3}\end{cases}}\)
b)\(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)
\(\Leftrightarrow10x-16-12x+15=12x-16+11\)
\(\Leftrightarrow-2x-1=12x-5\)
\(\Leftrightarrow14x=4\Leftrightarrow x=\frac{2}{7}\)
ét o ét các bn lm giúp mk ik,mk đang cak gấp ạ
Bài 2:
5x-(-2x-0,3)=2,4
=>5x+2x+0,3=2,4
=>7x=2,1
hay x=0,3