Tính: a. 9x^2/11y^2: 3x/2y: 6x/11y; b. (x^2-49)/(x-7)+x-2
Giải thích
a. 9x211y2:3x2y:6x11y
=9x211y2.2y3x.11y6x
=9x2.2y.11y11y2.3x.6x =1.
b. x2−49x−7+x−2
=x2−49x−7+(x−2)(x−7)x−7 =x2−49x−7+x2−9x+14x−7
=x2−49+x2−9x+14x−7=2x2−9x+35x−7
=(x−7)(2x+5)x−7
= 2x + 5.c. 11−x+11+x+21+x2+41+x4=1+x1−x2+1−x1−x2+21+x2+41+x4=21−x2+21+x2+41+x4=2(1+x2)1−x4+2(1−x2)1−x4+41+x4=2+2x21−x4+2−2x21−x4+41+x4=41−x4+41+x4=4(1+x4)1−x8+4(1−x4)1−x8=4+4x41−x8+4−4x41−x8 =81−x8.