15x103-15x2-15 tính nhanh
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\(942\times112-942\times11-942\)
\(=942\times\left(112-11-1\right)\)
\(=942\times100\)
\(=94200\)
\(\dfrac{1}{3}\times\dfrac{14}{15}+\dfrac{14}{15}\times\dfrac{2}{3}\)
\(=\dfrac{14}{15}\times\left(\dfrac{1}{3}+\dfrac{2}{3}\right)\)
\(=\dfrac{14}{15}\times\left(\dfrac{1+2}{3}\right)\)
\(=\dfrac{14}{15}\times\dfrac{3}{3}\)
\(=\dfrac{14}{15}\times1\)
\(=\dfrac{14}{15}\)
942 \(\times\) 112 - 942 \(\times\) 11 - 942
= 942 \(\times\) 112 - 942 \(\times\) 11 - 942 \(\times\) 1
= 942 \(\times\) ( 112 - 11 - 1)
= 942 \(\times\) 100
= 94200
![](https://rs.olm.vn/images/avt/0.png?1311)
Vì x=14 nên x+1=15
Thay 15=x+1 vào A(x) Ta có:
A(x)= x^15-(x+1)x^14+(x+1)x^13-(x+1)x^12+...+(x+1)x^3-(X+1)^2+(x+1)x-15
=x^15-x^15-x^14+x^14+x^13-x^13-...+X^4+x^3-X^3-x^2+x^2-x-15
=x-15
=> A(14)=14-15=-1
Vậy A(14)=-1
k mình nha
![](https://rs.olm.vn/images/avt/0.png?1311)
15 + 15 x 2 + 15 x 7 - 100
= ( 2 + 7 + 1 ) x 15
= 10 x 15
= 150
15 + 15x2 + 15x7 -100
= 15 x( 1+2+7 ) -100
= 15 x 10 -100
= 150-100
=50
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100-10+900-10+20
=(100+900)-(10+10)+20
=1000-20+20
=1000
b, 15x9+15x2-15
=15x(9+2-1)
=15x10
=150
K mik mik k lại
![](https://rs.olm.vn/images/avt/0.png?1311)
15x103-15x2-15
= (15x103)-(15x2)-15
= 1545 - (30 -15)
= 1545 - 15
= 1530
nhớ bấm đúng cho mik nha