74*x - 296=6956
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Đặt : \(A=\dfrac{4}{8\times11}+\dfrac{4}{11\times14}+...+\dfrac{4}{296\times299}\)
\(\dfrac{3\times A}{4}=\dfrac{3}{8\times11}+\dfrac{3}{11\times14}+...+\dfrac{3}{296\times299}\\ =\dfrac{1}{8}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{14}+...+\dfrac{1}{296}-\dfrac{1}{299}\\ =\dfrac{1}{8}-\dfrac{1}{299}\\ A=\left(\dfrac{1}{8}-\dfrac{1}{299}\right)\times4:3=\dfrac{97}{598}\)
Ta đặt
\(A=\dfrac{4}{8\times11}+\dfrac{4}{11\times14}+....+\dfrac{4}{296\times299}\)
\(\dfrac{3}{4}A=\dfrac{3}{8\times11}+\dfrac{3}{11\times14}+....+\dfrac{3}{296\times299}\)
\(\dfrac{3}{4}A=\dfrac{1}{8}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{14}+....+\dfrac{1}{296}-\dfrac{1}{299}\)
\(\dfrac{3}{4}A=\dfrac{1}{8}-\dfrac{1}{299}=\dfrac{291}{2392}\)
\(A=\dfrac{291}{2392}\div\dfrac{3}{4}\)
\(A=\dfrac{97}{598}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
74 * 11 - 74 * { 6 + 3 + 1}
= 74 * 11 - 74 * 10
= 74 * { 11 -10}
= 74 *1 = 74
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a. 2012 x ( 2011 - 1) + 2013 x ( 999 + 1 )
= 2012 x 2010 + 2013 x 1000
= 4044120 + 2013000
= 6057120
b. ( 191 - 109) x 5 + ( 624 - 296) : 4
= 82 x 5 + 328 : 4
= 410 + 82
= 492
b) = [5 x( 191 - 109 ) ] + [(624 - 296 ) : 4]
= (5 x 82) + (328 : 4)
= 410 + 82
= 492
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 24 × y : 20 = 480
24 × y = 480 × 20
24 × y = 9600
y = 9600 : 24
y = 400
b) 12862 : y - 296 = 61
12852 : y = 61 + 296
12852 : y = 357
y = 12852 : 357
y = 36
đó là 74
nhầm 98 đó bạn ko phải 74 đâu nha