1 tính bằng cách thuận tiện nhất
a, [ 63 *75 + 63*25 ] ; 7
b, [ 725 *32 ] ;5
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a) 25 × 34 × 4 = 25 × 4 × 34 = 100 × 34 = 3400
b) 128 × 93 + 128 × 7 = 128 × (93 + 7) = 128 × 100 = 12800
c) 57 × 63 - 47 × 63 = 63 × (57 – 47) = 63 × 10 = 630
a.25x34x4=25x4x34=100x34=340
b.128x93+128x7=128x(93+7)=128x100=12800\
c57x63-47x63=(57-47)x63=10x63=630
k cho mình nha
a, (25*4)*34=100*34=34000
b, 128*(93+7)=128*100=128000
c 63*(57-47)=63*10=630
\(\frac{21}{11}X\frac{22}{17}X\frac{68}{63}=\frac{952}{357} \)
\(\frac{5}{14}X\frac{7}{13}X\frac{6}{25}=\frac{3}{65}\)
21/11 x 22/17x68/63
= 7x3x2x11x4x17 / 11x17x7x3x3
=8/3
5/14x7/13x26/25
=5x7x26 / 14x13x25
= 5x7x13x2 / 7x2x13x5x5
=1/5
a; \(\dfrac{21}{11}\) x \(\dfrac{22}{17}\) x \(\dfrac{68}{63}\)
= \(\dfrac{21\times11\times2\times17\times4}{11\times17\times21\times3}\)
= \(\dfrac{11\times17\times21}{11\times17\times21}\) x \(\dfrac{2\times4}{3}\)
= 1 x \(\dfrac{8}{3}\)
= \(\dfrac{8}{3}\)
b; \(\dfrac{5}{14}\) \(\times\) \(\dfrac{7}{13}\) x \(\dfrac{26}{25}\)
= \(\dfrac{5\times7\times2\times13}{7\times2\times13\times5\times5}\)
= \(\dfrac{5\times7\times2\times13}{5\times7\times2\times13}\) x \(\dfrac{1}{5}\)
= 1 x \(\dfrac{1}{5}\)
= \(\dfrac{1}{5}\)