Tính nhẩm :
5x3=......
4x9=.......
3x5=......
6x3=.......
9x5=...........
Tính nhanh a) 5x4+9x5-5x3-10. b)4x7+4x6-4x3-4
a, 5 x 4 + 9 x 5 - 5 x 3 - 10
= 5 x ( 4 + 9 - 3) - 10
= 5 x ( 13 - 3) - 10
= 5 x 10 - 10
= 40
b, 4 x 7 + 4 x 6 - 4 x 3 - 4
= 4 x 7 + 4 x 6 - 4 x 3 - 4 x1
= 4 x ( 7 + 6 - 3 -1)
= 4 x 9
= 36
`5xx4+9xx5-5xx3-10`
`= 5 xx (4+9-3 -10)`
`= 5 xx 0`
`=0`
`-----`
`4 xx7 + 4 xx6 - 4xx3-4`
`=4 xx7 + 4 xx6 - 4xx3-4 xx 1`
`= 4xx (7+6-3-1)`
`= 4 xx 9`
`=36`
5.4 + 9.5 - 5.3 - 10
=5.4 + 9.5 - 5.3 - 5.2
=5.(4 + 9 - 3 - 2 )
=5. 8
= 40
b, 4 . 7 + 4 . 6 - 4 . 3 - 4
=4. ( 7 + 6 - 3 - 1 )
= 4. 9
= 36
Tính nhanh: 3 x 5 + 5 x 3 + 1 x 4 - 7 x 2 + 2 . x 2 x + 3 . x 4 - 7 x 2 + 2 3 x 5 + 5 x 3 + 1
Cho hai đa thức
P ( x ) = - 5 x 3 - 2 x + 4 x 4 + 3 + 3 x 2 - 4 x 4 + 10 x 3 - 8 , Q ( x ) = 6 x 2 + 5 x 3 - 3 x 5 + 4 + 8 x - 4 x 2 + 3 x 5 - 10 x
b. Tính M ( x ) = P ( x ) + Q ( x ) ; N ( x ) = P ( x ) - Q ( x )
b. M(x) = P(x) + Q(x) = 10x3 + 5x2 - 4x - 1 (0.5 điểm)
N(x) = P(x) - Q(x) = x2 - 9 (0.5 điểm)
P=5x3^11+4x3^12/3^9x5^2-3^9x2^3
Tính P.cần khẩnn cấp nha!!!
Cho hai đa thức
P ( x ) = - 5 x 3 - 2 x + 4 x 4 + 3 + 3 x 2 - 4 x 4 + 10 x 3 - 8 , Q ( x ) = 6 x 2 + 5 x 3 - 3 x 5 + 4 + 8 x - 4 x 2 + 3 x 5 - 10 x
d. Tính giá trị của đa thức A ( x ) = M ( x ) + 2 N ( x ) khi x = 1
d. A(x) = M(x) + 2N(x)
= 10x3 + 5x2 - 4x - 1 + 2(x2 - 9)
= 10x3 + 7x2 - 4x - 19 (0.5 điểm)
Thay x = 1 vào biểu thức ta có: A(1) = -6 (0.5 điểm)
2/5x3/4x6/15:4/9x5
\(\frac{2}{5}\times\frac{3}{4}\times\frac{6}{15}:\frac{4}{9}\times5=\frac{2\times3\times6\times9\times5}{5\times4\times15\times4}=\frac{27}{20}\)
2/5 x 3/4 x 6/15 : 4/9 x 5 = 6/20 x 6/15 : 4/9 x 5 = 36/300 : 4/9 x 5 = 324/1200 x 5 = 1620/1200
P=3x5-4x4+5x3-2x+7
Q=15x4-8x3+2x2-15x+8
a) tính P+Q
b)tính P-Q
a) \(P+Q=3x^5-4x^4+5x^3-2x+7+15x^4-8x^3+2x^2-15x+8=3x^5+11x^4-3x^3+2x^2-17x+15\)
b) \(P-Q=3x^5-4x^4+5x^3-2x+7-15x^4+8x^3-2x^2+15x-8=3x^5-19x^4+13x^3-2x^2+13x-1\)
a: Ta có: P+Q
\(=3x^5-4x^4+5x^3-2x+7+15x^4-8x^3+2x^2-15x+8\)
\(=3x^5+11x^4-3x^3-17x+15\)
b: Ta có: P-Q
\(=3x^5-4x^4+5x^3-2x+7-15x^4+8x^3-2x^2+15x-8\)
\(=3x^5-19x^4+13x^3+13x-1\)
5x3^11+4x3^12 /3^9x5^2-3^9x2^2
1/1x3 1/2x3 1/2x5 1/3x5 1/3x7 1/4x7 1/4x9
là sao ????=))
giữa các phân số là cộng hay trừ vậy???
\(\dfrac{1}{1.3}+\dfrac{1}{2.3}+\dfrac{1}{2.5}+\dfrac{1}{3.5}+\dfrac{1}{3.7}+\dfrac{1}{4.7}+\dfrac{1}{4.9}\)
\(=\dfrac{1}{1.3}+\dfrac{1}{3.2}+\dfrac{1}{2.5}+\dfrac{1}{5.3}+\dfrac{1}{3.7}+\dfrac{1}{7.4}+\dfrac{1}{4.9}\)
\(=\left(\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}+\dfrac{1}{8.9}\right):\dfrac{1}{2}\)
\(=\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}\right):\dfrac{1}{2}\)
\(=\left(\dfrac{1}{2}-\dfrac{1}{9}\right):\dfrac{1}{2}\)
\(=\dfrac{7}{18}:\dfrac{1}{2}\)
\(=\dfrac{7}{9}\)