In this paper we investigate Diophantine equations of the form class="mathmlsrc">title="View the MathML source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si2.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=47c6596ae4f6fee65fc372232353b70b">class="imgLazyJSB inlineImage" height="18" width="81" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0022314X15002450-si2.gif">class="mathContainer hidden">class="mathCode">, class="mathmlsrc">title="View the MathML source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si3.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=7b09602c5336e67810acd1b3b94d6b2d">class="imgLazyJSB inlineImage" height="18" width="132" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0022314X15002450-si3.gif">class="mathContainer hidden">class="mathCode">, where class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si4.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=5b8841dd6cf489f917198b84e099530d" title="Click to view the MathML source">m=3class="mathContainer hidden">class="mathCode"> or class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si5.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=ab8d36fe8fe36fae90f36515d7f6a137" title="Click to view the MathML source">m=4class="mathContainer hidden">class="mathCode"> and G is a specific homogeneous quintic form. First, we prove that if class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si6.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=2da86d03b0f08243b70c486ab962d951" title="Click to view the MathML source">F(x,y,z)=x2+y2+az2+bxy+cyz+dxz∈Z[x,y,z]class="mathContainer hidden">class="mathCode"> and class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si164.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=5c5ad56b194608e73919f7d43494e145" title="Click to view the MathML source">(b−2,4a−d2,d)≠(0,0,0)class="mathContainer hidden">class="mathCode">, then for all class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si133.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=4ce0208c711ff5ba80cf764b6f1b62dc" title="Click to view the MathML source">n∈Z鈭杮0}class="mathContainer hidden">class="mathCode"> the Diophantine equation class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si9.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=ead3ba96051828d96d12d0c060cd99c3" title="Click to view the MathML source">t2=nxyzF(x,y,z)class="mathContainer hidden">class="mathCode"> has a solution in polynomials x, y, z, t with integer coefficients, with no polynomial common factor of positive degree. In case class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si10.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=dcda36abd583123af4421a592f64ec2d" title="Click to view the MathML source">a=d=0class="mathContainer hidden">class="mathCode">, class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si11.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=410df7a47b302272b461a8409aa03f22" title="Click to view the MathML source">b=2class="mathContainer hidden">class="mathCode"> we prove that there are infinitely many primitive integer solutions of the Diophantine equation under consideration. As an application of our result we prove that for each class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si12.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=4b67652db3121dfeb6ebd527d50e1888" title="Click to view the MathML source">n∈Q鈭杮0}class="mathContainer hidden">class="mathCode"> the Diophantine equation
has a solution in polynomials which are co-prime over class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si18.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=8c5124df2c311ba45db98c4afa25cf92" title="Click to view the MathML source">Z[t]class="mathContainer hidden">class="mathCode">. Moreover, we show how a modification of the presented method can be used in order to prove that for each class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si12.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=4b67652db3121dfeb6ebd527d50e1888" title="Click to view the MathML source">n∈Q鈭杮0}class="mathContainer hidden">class="mathCode">, the Diophantine equation
has a solution in polynomials which are co-prime over class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X15002450&_mathId=si18.gif&_user=111111111&_pii=S0022314X15002450&_rdoc=1&_issn=0022314X&md5=8c5124df2c311ba45db98c4afa25cf92" title="Click to view the MathML source">Z[t]class="mathContainer hidden">class="mathCode">.