Nho 73 Questions 855 Answers 0 Best Answers 20 Points View Profile0 Nho Asked: October 18, 20202020-10-18T21:35:53+00:00 2020-10-18T21:35:53+00:00In: Môn Toántìm x biết: 5x(2 x-7)=21-2x(7-5x)0tìm x biết: 5x(2 x-7)=21-2x(7-5x) ShareFacebookRelated Questions Một nền nhà hình chữ Nhật có chiều dài 24m, rộng bằng 1/6 chiều dài. Người ta định lát nền Tìm tập xác định của hàm số y = (tan x) / (cos x - 1) Phân tích các đa thức sau thành nhân tử: X^3-4x^2-9x+36 2 AnswersOldestVotedRecentMaris 68 Questions 833 Answers 0 Best Answers 20 Points View Profile Maris 2020-10-18T21:37:00+00:00Added an answer on October 18, 2020 at 9:37 pm `5x(2x-7)=21-2x(7-5x)``<=> 10x^2 – 35x = 21 – 14x + 10x^2``<=> 10x^2-35x+14x-10x^2=21``<=> -21x = 21``<=> x = -1`Vậy `x = – 1`0Reply Share ShareShare on FacebookSapo 63 Questions 813 Answers 0 Best Answers 20 Points View Profile Sapo1 2020-10-18T21:37:13+00:00Added an answer on October 18, 2020 at 9:37 pm `5x(2x – 7) = 21 – 2x(7 – 5x)``<=> 10x^2 – 35x = 21 – 14x + 10x^2``<=> -21x = 21``<=> x = -1`0Reply Share ShareShare on FacebookLeave an answerLeave an answerCancel reply Featured image Select file Browse Save my name, email, and website in this browser for the next time I comment.
Maris
`5x(2x-7)=21-2x(7-5x)`
`<=> 10x^2 – 35x = 21 – 14x + 10x^2`
`<=> 10x^2-35x+14x-10x^2=21`
`<=> -21x = 21`
`<=> x = -1`
Vậy `x = – 1`
Sapo
`5x(2x – 7) = 21 – 2x(7 – 5x)`
`<=> 10x^2 – 35x = 21 – 14x + 10x^2`
`<=> -21x = 21`
`<=> x = -1`