`\qquad 5x(x^2-3)+x^2(7-5x)-7x^2`
`=5x^3-15x+7x^2-5x^3-7x^2`
`=-15x`
Thay `x=-5` vào biểu thức ta có:
`\qquad -15.(-5)=75`
Vậy giá trị bt là `75` khi `x=-5`
Đáp án+Giải thích các bước giải:
Thay x = - 5 vào biểu thức đã cho ta được :
5.(-5).{(-5)² - 3} + (-5)² .(7 + 5.5) - 7.(-5)²
= -25. 22 + 25 . 32 - 7.25
= -25.(22 - 32 + 7)
= -25 . (-3)
= 75
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Calli Min Tổng Nl: Hóng ~ ARMY dạt vào đây :)
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