\[ y'(x)^4-(y(x)-a)^3 (y(x)-b)^2=0 \] ✓ Mathematica : cpu = 0.690435 (sec), leaf count = 323
\[\left \{\left \{y(x)\to \text {InverseFunction}\left [-\frac {4 \sqrt [4]{a-\text {$\#$1}} \sqrt {\frac {\text {$\#$1}-b}{a-b}} \, _2F_1\left (\frac {1}{4},\frac {1}{2};\frac {5}{4};\frac {a-\text {$\#$1}}{a-b}\right )}{\sqrt {b-\text {$\#$1}}}\& \right ]\left [-\sqrt [4]{-1} x+c_1\right ]\right \},\left \{y(x)\to \text {InverseFunction}\left [-\frac {4 \sqrt [4]{a-\text {$\#$1}} \sqrt {\frac {\text {$\#$1}-b}{a-b}} \, _2F_1\left (\frac {1}{4},\frac {1}{2};\frac {5}{4};\frac {a-\text {$\#$1}}{a-b}\right )}{\sqrt {b-\text {$\#$1}}}\& \right ]\left [\sqrt [4]{-1} x+c_1\right ]\right \},\left \{y(x)\to \text {InverseFunction}\left [-\frac {4 \sqrt [4]{a-\text {$\#$1}} \sqrt {\frac {\text {$\#$1}-b}{a-b}} \, _2F_1\left (\frac {1}{4},\frac {1}{2};\frac {5}{4};\frac {a-\text {$\#$1}}{a-b}\right )}{\sqrt {b-\text {$\#$1}}}\& \right ]\left [-(-1)^{3/4} x+c_1\right ]\right \},\left \{y(x)\to \text {InverseFunction}\left [-\frac {4 \sqrt [4]{a-\text {$\#$1}} \sqrt {\frac {\text {$\#$1}-b}{a-b}} \, _2F_1\left (\frac {1}{4},\frac {1}{2};\frac {5}{4};\frac {a-\text {$\#$1}}{a-b}\right )}{\sqrt {b-\text {$\#$1}}}\& \right ]\left [(-1)^{3/4} x+c_1\right ]\right \}\right \}\] ✓ Maple : cpu = 0.23 (sec), leaf count = 144
\[ \left \{ x-\int ^{y \left ( x \right ) }\!{\frac {1}{\sqrt [4]{ \left ( {\it \_a}-a \right ) ^{3} \left ( -b+{\it \_a} \right ) ^{2}}}}{d{\it \_a}}-{\it \_C1}=0,x-\int ^{y \left ( x \right ) }\!{-i{\frac {1}{\sqrt [4]{- \left ( -{\it \_a}+a \right ) ^{3} \left ( b-{\it \_a} \right ) ^{2}}}}}{d{\it \_a}}-{\it \_C1}=0,x-\int ^{y \left ( x \right ) }\!{i{\frac {1}{\sqrt [4]{- \left ( -{\it \_a}+a \right ) ^{3} \left ( b-{\it \_a} \right ) ^{2}}}}}{d{\it \_a}}-{\it \_C1}=0,x-\int ^{y \left ( x \right ) }\!-{\frac {1}{\sqrt [4]{- \left ( -{\it \_a}+a \right ) ^{3} \left ( b-{\it \_a} \right ) ^{2}}}}{d{\it \_a}}-{\it \_C1}=0,y \left ( x \right ) =a,y \left ( x \right ) =b \right \} \]