5. Найдите диагональ прямоугольника, если его периметр равен 28 см, а периметр одного из треугольников, на которые диаго- наль разделила прямоугольник, равен 24 см. трапеции
In the first picture, the girl is listening to music and from her face, we can understand that she is enjoying it.
Then, in the second picture, the boy is drawing a picture with colored pencils.
In the third, the group of kids is doing a piece of art. The boy with brown hair is drawing a picture, while a girl with black hair is doing pottery. (По картинке я не понял что делают другие)
In the last picture, the kids are playing in the band. We can see that the first boy in a yellow T-shirt is singing a song while his friends are playing on different instruments.
In the first picture, the girl is listening to music and from her face, we can understand that she is enjoying it.
Then, in the second picture, the boy is drawing a picture with colored pencils.
In the third, the group of kids is doing a piece of art. The boy with brown hair is drawing a picture, while a girl with black hair is doing pottery. (По картинке я не понял что делают другие)
In the last picture, the kids are playing in the band. We can see that the first boy in a yellow T-shirt is singing a song while his friends are playing on different instruments.
Объяснение: 1) Упростим выражение.
2а³+9 -2 (а+1)(а²-а+1)=
=2а³+9- 2(а³+1³)= 2а³+9-2а³-2=7
Проверим на полном выражении: при а=0,5
2*(0,5)³+9-2(0,5+1) (0,5²-0,5+1)=2*0,125+9 - 2*1,5*(0,25+0,5)=
= 0,25+9-3*0,75= 9,25-2,25=7
2)Упростим выражение:
х(х+2)(х-2) -(х-3)(х²+3х+9)=
=х(х²-4) - (х³-27) =х³-4х-х³+27= -4х+27
при х=1/4
-4*(1/4) +9=-1+27=26
Проверим на полном выражении: при х =1/4=0,25
0,25(0,25+2)(0,25-2)- (0,25-3)(0,25²+3*0,25+9)=
=0,25*2,25*(-1,75) - (- 2,75 ) *(0,0625+0,75+9)=
= -0,984375 - (-2,75)* 9,8125= 26,984375- 0,984375=
=26
3) 3(b-1)²+(b+2)(b²+2b+4) - (b+1)²=
= 3(b²-2b+1)+(b+2)( b²+2b+2²)-(b²+2b+1)=
= 3b²-6b+3+b³+2b²+4b+2b²+4b+8-b²-2b-1=
=(3b²+2b²+2b²-b²)+(-6b+4b+4b-2b)+(3+8-1)+b³=
= 6b²+10+b³= b²( 6+b)+10
Может можно как-то проще сократить...
b=-1/3
(-1/3)² (6+1/3)+10= 1/9 * 6 1/3 +10 = 19/27 + 10=10 19/27
4) в выражении знак пропущен...