Ai đúng và nhanh 3 tick nha
Bài 5 Tìm x biết :
a) \(16x^2-\left(4x-5\right)^2=15\) b) \(\left(2x+3\right)^2-4\left(x-1\right)\left(x+1\right)=49\)
c) \(\left(2x+1\right)\left(1-2x\right)+\left(1-2x\right)^2=18\) d) \(2\left(x+1\right)^2-\left(x-3\right)\left(x+3\right)-\left(x-4\right)^2=0\)
e) \(\left(x-5\right)^2-x\left(x-4\right)=9\) f) \(\left(x-5\right)^2+\left(x-4\right)\left(1-x\right)=0\)
Bài 6 : Chứng minh đẳng thức : \(\left(a-b\right)^2=\left(a+b\right)^2-4ab\)
Bài 6
\(\left(a-b\right)^2=a^2-2ab+b^2\)
\(=\left(a^2+2ab+b^2\right)-4ab\)
\(=\left(a+b\right)^2-4ab\)
Bài 5 :
\(a,16x^2-\left(4x-5\right)^2=15\)
\(16x^2-16x^2+40x-25-15=0\)
\(40x-40=0\)
\(40x=40\)
\(x=1\)
\(b,\left(2x+3\right)^2-4\left(x-1\right)\left(x+1\right)=49\)
\(4x^2+12x+9-4x^2+4=49\)
\(12x=36\)
\(x=3\)
\(c,\left(2x+1\right)\left(2x-1\right)+\left(1-2x\right)^2=18\)
\(4x^2-1+1-4x+4x^2=18\)
\(8x^2-4x-18=0\)
\(2\left(4x^2-2x-9\right)=0\)
\(x=\frac{1-\sqrt{37}}{4}\)
\(d,2\left(x+1\right)^2-\left(x-3\right)\left(x+3\right)-\left(x-4\right)^2=0\)
\(2x^2+4x+2-x^2+9-x^2+8x-16=0\)
\(12x=4\)
\(x=\frac{1}{3}\)
Máy mình bị lỗi nên bạn chịu khó nhìn hình mình chụp nha. ^^
Link: https://imgur.com/a/p0MkTlQ
