$Dạng$ `4` `:`
`B1:`
`l)(x-47)-115=0`
`x-47 = 0+115`
`x-47 =115`
`x =115+47`
`x =162`
$Dạng$ `5:`
`B1:`
`a,2a b, 2a+1 c, 3a d, 3a+1`
`a,4a b,4a+1 c,4a+3 d,3a+2`
`a, a; a+1 b, 2a, 2a+2 c, 2a+1;2a+3`
`B2:`
`a, 2(x+1) b, 2(x+2) c, 3(3+x) d,2(x-1) e,4(2-x) f,5(3-x)`
`a, 2x(y-1) b,3x(6-y) c,3x(2+y) d,2(2x-1)`
`B3:`
`a, S= (49+1)×25/2=625`
`b, A=(2x+1+1)×(x+1)/2=(x+1)^2`
`c, B=(2014+2)×1007/2=1015056`
`d, C=(2x+2)×x/2=x²+x`
$#UMR#$
