87*23+19*93+70*87 295-(31-2^2*5)^2 0:ích=0 2 mũ ích :2^5=1 05/07/2021 Bởi Clara 87*23+19*93+70*87 295-(31-2^2*5)^2 0:ích=0 2 mũ ích :2^5=1
Đáp án: `a) 9858.` `b) 174.` `c) 0.` `d) 5.` Giải thích các bước giải: `a) 87 × 23 + 19 × 93 + 70 × 87.` `= (87 × 23 + 70 × 87) + 19 × 93.` `= 87 × (23 + 70) + 19 × 93.` `= 87 × 93 + 19 × 93.` `= (87 + 19) × 93.` `= 106 × 93.` `= 9858.` `b) 295 – (31 – 2^2 × 5)^2.` `= 295 – (31 – 4 × 5)^2.` `= 295 – (31 – 20)^2.` `= 295 – 11^2.` `= 295 – 121.` `= 174.` `c) 0 ÷ x = 0.` `⇒ x = 0.` `d) 2^x ÷ 2^5 = 1.` `⇒ 2^{x – 5} = 1.` `⇒ 2^{x – 5} = 2^0.` `⇒ x – 5 = 0.` `⇒ x = 5.` Bình luận
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Đáp án:
`a) 9858.`
`b) 174.`
`c) 0.`
`d) 5.`
Giải thích các bước giải:
`a) 87 × 23 + 19 × 93 + 70 × 87.`
`= (87 × 23 + 70 × 87) + 19 × 93.`
`= 87 × (23 + 70) + 19 × 93.`
`= 87 × 93 + 19 × 93.`
`= (87 + 19) × 93.`
`= 106 × 93.`
`= 9858.`
`b) 295 – (31 – 2^2 × 5)^2.`
`= 295 – (31 – 4 × 5)^2.`
`= 295 – (31 – 20)^2.`
`= 295 – 11^2.`
`= 295 – 121.`
`= 174.`
`c) 0 ÷ x = 0.`
`⇒ x = 0.`
`d) 2^x ÷ 2^5 = 1.`
`⇒ 2^{x – 5} = 1.`
`⇒ 2^{x – 5} = 2^0.`
`⇒ x – 5 = 0.`
`⇒ x = 5.`