Question

Answer 1

Câu 8:

Xét ΔABC có \(\widehat{BAC}+\widehat{ACB}+\widehat{ABC}=180^0\)

=>\(\widehat{BAC}+\widehat{ACB}=180^0-68^0=112^0\)

=>\(2\cdot\widehat{DAC}+2\cdot\widehat{DCA}=112^0\)

=>\(2\left(\widehat{DAC}+\widehat{DCA}\right)=112^0\)

=>\(\widehat{DAC}+\widehat{DCA}=56^0\)

XétΔDAC có \(\widehat{DAC}+\widehat{DCA}+\widehat{ADC}=180^0\)

=>\(\widehat{ADC}+56^0=180^0\)

=>\(\widehat{ADC}=124^0\)

Câu 7:

ĐKXĐ: x<>1

Để M là số nguyên thì \(2x-5⋮x-1\)

=>\(2x-2-3⋮x-1\)

=>\(-3⋮x-1\)

=>\(x-1\in\left\{1;-1;3;-3\right\}\)

=>\(x\in\left\{2;0;4;-2\right\}\)