Toán Lớp 8: Tính hợp lý a, 75.20,9+5².20,9 b, -8.40+2.108+24 c, 86.15+150.1,4

Question

Toán Lớp 8:  Tính hợp lý a, 75.20,9+5².20,9 b, -8.40+2.108+24 c, 86.15+150.1,4

cobebongdem · Answer

Giải đáp:

Lời giải và giải thích chi tiết:

a)75.20,9 + 5^2.20,9
=(75+$5^{2}$ )20,9
= 2.090

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b) -8.40+2.108+24

$=$ $- 8$ . $8$ . $5$ $+$ $8$ . $27$ + $8$ . $3$

$=$ $- 8$ . $(40 - 27 - 3)$

$=$ $- 8$ . $10$

$=$ $- 80$

$- 80$

c) $86$ . $15$ $+$ $150$ . $1, 4$

$=$ $86$ . $15$ $+$ $5$ . $10$ . $1, 4$

$=$ $86$ . $15$ $+$ $5$ . $14$

$=$ $15$ . $(86 + 14)$

$=$ $15$ . $100$

$=$ $1500$

hiennhi98 · Answer

a,  (75 ) .  (20,9 )  (+ )  (5&sup2; ) .  (20,9 )      (= )  ((75 + 5&sup2;) ) .  (20,9 )       (= )  (100 ) .  (20,9 )      (= )  (2090 )     b,  (-8 ) .  (40 )  (+ )  (2 ) .  (108 )  (+ )  (24 )      (= )  (-8 ) .  (8 ) . (5 )  (+ )  (8 ) .  ( 27 ) +  (8 ) .  (3 )      (= )  (-8 ) .  ((40 - 27 - 3) )      (= )  (-8 ) .  (10 )      (= )  (-80 )     c,  (86 ) .  (15 )  (+ )  (150 ) .  (1,4 )      (= )   (86 ) .  (15 )  (+ )   (5 ) .  (10 ) .  (1,4 )      (= )   (86 ) .  (15 )  (+ )   (5 ) .  (14 )      (= )  (15 ) .  ((86 + 14) )      (= )  (15 ) .  (100 )      (= )  (1500 )