Đáp án:
Giải thích các bước giải:
`8,(3/7+1/2)^2=(3/7)^2+2(3/7)(1/2)+(1/2)^2=9/49+3/7+1/4`
`9, 21/41+9/45+26/47+4/5`
`10, (5^4.(20^4))/(25^4.(4^5))=(5^4.(2^2.(5))^4)/((5^2)^4.(2^2)^5)=(5^8.(2^8))/(5^8.(2^10))=1/2^2=1/4`
bài 5:
`1, x+1/4=4/3`
`⇔x=4/3-1/4`
`⇔x=13/12`
`2, -x-2/3=-6/7`
`⇔-x=-6/7+2/3`
`⇔-x=-4/21`
`⇔x=4/21`
`3, 4/5-x=1/3`
`⇔x=4/5-1/3`
`⇔x=7/15`
`4, x^2=16`
`⇔x=+-4`
