Toán Câu 25: Tìm số nguyên x biết: a) -5.(-x + 7) – 3.(-x – 5) = -4.(12 – x ) + 48 c) 7.(-x – 7) – 5.(-x – 3) = 12.(3 – x) b) -2.(15 – 3x) – 4.( 07/07/2021 By Ivy Câu 25: Tìm số nguyên x biết: a) -5.(-x + 7) – 3.(-x – 5) = -4.(12 – x ) + 48 c) 7.(-x – 7) – 5.(-x – 3) = 12.(3 – x) b) -2.(15 – 3x) – 4.(-7x + 8) = -5 – 9.(-2x + 1) d) 5.(-3x – 7) – 4.(-2x – 11) = 7.(4x + 10) + 9
Bạn tham khảo: $a) -5.(-x + 7) – 3.(-x – 5) = -4.(12 – x ) + 48$ $⇔ -5x – 35 + 3x + 15 = -48 +4x + 48$$⇔ -5x + 3x – 4x = -48 + 48 – 15 + 35$$⇔ -2x = 20$$⇔ x = -10$ $c) 7.(-x – 7) – 5.(-x – 3) = 12.(3 – x)$ $⇔ -7x -49 + 5x + 15 = 36 – 12x$$⇔ -7x + 5x + 12x = 36 – 15 + 49$ $⇔ 10x = 70$$⇔ x = 7$ $b) -2.(15 – 3x) – 4.(-7x + 8) = -5 – 9.(-2x + 1)$ $⇔ -30 + 6x + 28x – 32 = -5 + 18x – 9$$⇔ 6x + 28x – 18x = -5 -9+30+32$$⇔ 16x = 48$$⇔ x = 3$ $d) 5.(-3x – 7) – 4.(-2x – 11) = 7.(4x + 10) + 9$$⇔ -15x – 35 + 8x + 44 = 28x + 70 + 9$$⇔ -15x + 8x – 28x = 70 + 9 – 44 + 35$$⇔ -35x = 70$$⇔ x = -2$ Trả lời