下列计算正确的是( )
下列计算正确的是 ( )
3 a 2 + 4 a 2 = 7 a 4
a 2 ⋅ 1 a = 1
− 18 + 12 ÷ ( − 3 2 ) = 4
a 2 a − 1 − a − 1 = 1 a − 1
如图,从边长为(a+3)cm的大正方形纸片中剪去一个边长为(a+1)cm的小正方形(a>0),剩余部分沿虚线剪开,重新拼成一个长方形(不重叠无缝隙),则此长方形的周长为( )
a 3 + a 3 = a 6
2 a 3 - a 3 = 1
a 2 ⋅ a 3 = a 5
( a 2 ) 3 = a 5
若,则=_________.
下列计算中,正确的是 ( )
( a + 3 ) 2 = a 2 + 9
a 8 ÷ a 4 = a 2
2 ( a - b ) = 2 a - b
a 2 + a 2 = 2 a 2
分解因式(1)2n2(m-2)+8(2-m)(2)-8a2b+2a3+8ab2
a 2 + a 2 = a 4
2 a - a = 1
2 a ⋅ ( - 3 a ) = - 6 a 2
2 a + 3 b = 5 ab
5 a 3 b ÷ ab = 5 a 2 b
( 2 a + b ) 2 = 4 a 2 + b 2
( − 2 a 2 b 3 ) 3 = − 8 a 6 b 9
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
下列运算正确的是 ( )
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 2 ) 3 = a 6
a 3 ⋅ a 2 = a 6
先化简,再求值:3-[7x-2(6x-8)-],其中x=-1.