`a):`
`9x^2 - 64 = 0`
`⇔ (3x−8)(3x+8)=0`
\(\left[ \begin{array}{l}x= \dfrac{8}{3} \\x=- \dfrac{8}{3} \end{array} \right.\)
`b):`
`4x^2 - 12x + 9 = 0`
`⇔` \(\left[ \begin{array}{l}a+b=-12\\ab=4×9=36\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}-1,-36\\-2,-18\\-3,-12\\-4,-9\\-6,-6\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}-1-36=-37\\-2-18=-20\\-3-12=-15\\-4-9=-13\\-6-6=-12\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}a=-6\\b=-6\end{array} \right.\)
`⇔ (4x^2−6x)+(−6x+9)`
`⇔ 2x(2x−3)−3(2x−3)`
`⇔ (2x−3)(2x−3)`
`⇔ (2x−3)^2`
`x = 3/2`
`c):`
`(2x - 5)^2 + (4 - 3x)^2 - 11x(x - 2) = 5`
`⇔ 4x^2−20x+25+(4−3x)^2−11x(x−2)=5`
`⇔ 4x^2−20x+25+16−24x+9x^2−11x(x−2)=5`
`⇔ 4x^2−20x+41−24x+9x^2−11x(x−2)=5`
`⇔ 4x^2−44x+41+9x^2−11x(x−2)=5`
`⇔ 13x^2−44x+41−11x(x−2)=5`
`⇔ 13x^2−44x+41−11x(x−2)−5=0`
`⇔ 13x^2−44x+41−11x^2+22x−5=0`
`⇔ 2x^2−44x+41+22x−5=0`
`⇔ 2x^2−22x+41−5=0`
`⇔ 2x^2−22x+36=0`
`⇔ x^2−11x+18=0`
`⇔` \(\left[ \begin{array}{l}a+b=-11\\ab=1×18=18\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}-1,-18\\-2,-9\\-3,-6\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}-1-18=-19\\-2-9=-11\\-3-6=-9\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}a=-9\\b=-2\end{array} \right.\)
`⇔ (x^2−9x)+(−2x+18)` `⇔ x(x−9)−2(x−9)`
`⇔ (x−9)(x−2)`
\(\left[ \begin{array}{l}x=9\\x=2\end{array} \right.\)
Cho mình xin hay nhất nha bạn!!!!
@Drew Mclntyre
