下列各式中,正确的是 ( )
x + 2 x = 3 x 2
− ( x − y ) = − x − y
( x 2 ) 3 = x 5
x 5 ÷ x 3 = x 2
化简:2x2+1-3x+7-2x2+5x.
下列运算正确的是 ( )
a - 2 = - a 2
a 2 + a 3 = a 5
a 2 ⋅ a 3 = a 6
( a 2 ) 3 = a 6
下列计算正确的是 ( )
a + a 2 = a 3
( 2 a 2 ) 3 = 2 a 6
a 6 ÷ a 2 = a 3
a 3 ⋅ a 2 = a 5
下列计算正确的是 ( )
a 3 + a 2 = a 5
a 3 ÷ a 2 = a
3 a 3 ⋅ 2 a 2 = 6 a 6
( a - 2 ) 2 = a 2 - 4
化简:的结果是( )
下列运算结果正确的是 ( )
x 2 + x 3 = x 5
( − a − b ) 2 = a 2 + 2 ab + b 2
( 3 x 3 ) 2 = 6 x 6
2 + 3 = 5
下列运算中,正确的是 ( )
a 2 + a = a 3
( - ab ) 2 = - a b 2
a 5 ÷ a 2 = a 3
a 5 ⋅ a 2 = a 10
计算: 2 a + 3 a = .
a 2 + a 2 = 2 a 4
a 2 ⋅ a = a 3
( 3 a ) 2 = 6 a 2
a 6 + a 2 = a 3
2 x 2 + 3 x 3 = 5 x 5
( − 2 x ) 3 = − 6 x 3
( x + y ) 2 = x 2 + y 2
( 3 x + 2 ) ( 2 − 3 x ) = 4 − 9 x 2
下列式子正确的是 ( )
a 3 - a 2 = a
a 3 ⋅ a 2 = a 6
( a 2 ) 3 = a 5
先化简,再求值:3-[7x-2(6x-8)-],其中x=-1.